NAME

Math::MPFR - perl interface to the MPFR (floating point) library.

DEPENDENCIES

This module needs the MPFR and GMP C libraries. (Install GMP
first as it is a pre-requisite for MPFR.)

The GMP library is availble from http://gmplib.org
The MPFR library is available from http://www.mpfr.org/

DESCRIPTION

A bigfloat module utilising the MPFR library. Basically
this module simply wraps the 'mpfr' floating point functions
provided by that library.
Operator overloading is also available.
The following documentation heavily plagiarises the mpfr
documentation.
See also the Math::MPFR test suite for some examples of
usage.

SYNOPSIS

use Math::MPFR qw(:mpfr);

# '@' can be used to separate mantissa from exponent. For bases
# that are <= 10, 'e' or 'E' can also be used.
# Use single quotes for string assignment if you're using '@' as
# the separator. If you must use double quotes, you'll have to 
# escape the '@'.

my $str = '.123542@2'; # mantissa = (.)123452
                      # exponent = 2
#Alternatively:
# my $str = ".123542\@2";
# or:
# my $str = '12.3542';
# or:
# my $str = '1.23542e1';
# or:
# my $str = '1.23542E1';

my $base = 10;
my $rnd = MPFR_RNDZ; # See 'ROUNDING MODE'

# Create an Math::MPFR object that holds an initial
# value of $str (in base $base) and has the default
# precision. $bn1 is the number. $nok will either be 0 
# indicating that the string was a valid number string, or
# -1, indicating that the string contained at least one
# invalid numeric character. 
# See 'COMBINED INITIALISATION AND ASSIGNMENT', below.
my ($bn1, $nok) = Rmpfr_init_set_str($str, $base, $rnd);

# Or use the new() constructor - also documented below
# in 'COMBINED INITIALISATION AND ASSIGNMENT'.
# my $bn1 = Math::MPFR->new($str);

# Create another Math::MPFR object with precision
# of 100 bits and an initial value of NaN.
my $bn2 = Rmpfr_init2(100);

# Assign the value -2314.451 to $bn1.
Rmpfr_set_d($bn2, -2314.451, MPFR_RNDN);

# Create another Math::MPFR object that holds
# an initial value of NaN and has the default precision.
my $bn3 = Rmpfr_init();

# Or using instead the new() constructor:
# my $bn3 = Math::MPFR->new();

# Perform some operations ... see 'FUNCTIONS' below.
# see 'OPERATOR OVERLOADING' below for docs re
# operator overloading

.
.

# print out the value held by $bn1 (in octal):
print Rmpfr_get_str($bn1, 8, 0, $rnd), "\n"; 

# print out the value held by $bn1 (in decimal):
print Rmpfr_get_str($bn1, 10, 0, $rnd), "\n";
# or just make use of overloading :
print $bn1, "\n"; # is base 10, and uses 'e' rather than '@'.

# print out the value held by $bn1 (in base 16) using the
# 'TRmpfr_out_str' function. (No newline is printed - unless
# it's supplied as the optional fifth arg. See the
# 'TRmpfr_out_str' documentation below.)
TRmpfr_out_str(*stdout, 16, 0, $bn1, $rnd);

ROUNDING MODE

One of 4 values:
 GMP_RNDN (numeric value = 0): Round to nearest.
 GMP_RNDZ (numeric value = 1): Round towards zero.
 GMP_RNDU (numeric value = 2): Round towards +infinity.
 GMP_RNDD (numeric value = 3): Round towards -infinity.

With the release of mpfr-3.0.0, the same rounding values
are renamed to:
 MPFR_RNDN (numeric value = 0): Round to nearest.
 MPFR_RNDZ (numeric value = 1): Round towards zero.
 MPFR_RNDU (numeric value = 2): Round towards +infinity.
 MPFR_RNDD (numeric value = 3): Round towards -infinity.

You can use either rendition with Math-MPFR-3.0 or later.

The mpfr-3.0.0 library also provides:
 MPFR_RNDA (numeric value = 4): Round away from zero.

It, too, can be used with Math-MPFR-3.0 or later, but 
will cause a fatal error iff the mpfr library against
which Math::MPFR is built is earlier than version 3.0.0.

 The `round to nearest' mode works as in the IEEE
 P754 standard: in case the number to be rounded
 lies exactly in the middle of two representable 
 numbers, it is rounded to the one with the least
 significant bit set to zero.  For example, the 
 number 5, which is represented by (101) in binary,
 is rounded to (100)=4 with a precision of two bits,
 and not to (110)=6.  This rule avoids the "drift"
 phenomenon mentioned by Knuth in volume 2 of 
 The Art of Computer Programming (section 4.2.2,
 pages 221-222).

 Most Math::MPFR functions take as first argument the
 destination variable, as second and following arguments 
 the input variables, as last argument a rounding mode,
 and have a return value of type `int'. If this value
 is zero, it means that the value stored in the 
 destination variable is the exact result of the 
 corresponding mathematical function. If the
 returned value is positive (resp. negative), it means
 the value stored in the destination variable is greater
 (resp. lower) than the exact result.  For example with 
 the `GMP_RNDU' rounding mode, the returned value is 
 usually positive, except when the result is exact, in
 which case it is zero.  In the case of an infinite
 result, it is considered as inexact when it was
 obtained by overflow, and exact otherwise.  A
 NaN result (Not-a-Number) always corresponds to an
 inexact return value.

MEMORY MANAGEMENT

Objects are created with new() or with the Rmpfr_init*
functions. All of these functions return an object that has
been blessed into the package Math::MPFR.
They will therefore be automatically cleaned up by the
DESTROY() function whenever they go out of scope.

For each Rmpfr_init* function there is a corresponding function
called Rmpfr_init*_nobless which returns an unblessed object.
If you create Math::MPFR objects using the '_nobless'
versions, it will then be up to you to clean up the memory
associated with these objects by calling Rmpfr_clear($op) 
for each object, or Rmpfr_clears($op1, $op2, ....).
Alternatively such objects will be cleaned up when the script
ends. I don't know why you would want to create unblessed
objects. The point is that you can if you want to.
The test suite does no testing of unblessed objects ... beware
of bugs if you go down that path.

MIXING GMP OBJECTS WITH MPFR OBJECTS

Some of the Math::MPFR functions below take as arguments
one or more of the GMP types mpz (integer), mpq
(rational) and mpf (floating point). (Such functions are
marked as taking mpz/mpq/mpf arguments.)
For these functions to work you need to have loaded either:

1) Math::GMP from CPAN. (This module provides access to mpz
   objects only - NOT mpf and mpq objects.)

AND/OR

2) Math::GMPz (for mpz types), Math::GMPq (for mpq types)
   and Math::GMPf (for mpf types). 

You may also be able to use objects from the GMP module
that ships with the GMP sources. I get occasional 
segfaults when I try to do that, so I've stopped
recommending it - and don't support the practice.     

FUNCTIONS

These next 3 functions are demonstrated above:
$rop = Rmpfr_init();
$rop = Rmpfr_init2($p);
$str = Rmpfr_get_str($op, $base, $digits, $rnd); # 1 < $base < 37 
The third argument to Rmpfr_get_str() specifies the number of digits
required to be output in the mantissa. (Trailing zeroes are removed.) 
If $digits is 0, the number of digits of the mantissa is chosen
large enough so that re-reading the printed value with the same
precision, assuming both output and input use rounding to nearest,
will recover the original value of $op.

The following functions are simply wrappers around an mpfr
function of the same name. eg. Rmpfr_swap() is a wrapper around
mpfr_swap().

"$rop", "$op1", "$op2", etc. are Math::MPFR objects - the
return value of one of the Rmpfr_init* functions. They are in fact 
references to mpfr structures. The "$op" variables are the operands
and "$rop" is the variable that stores the result of the operation.
Generally, $rop, $op1, $op2, etc. can be the same perl variable 
referencing the same mpfr structure, though often they will be 
distinct perl variables referencing distinct mpfr structures.
Eg something like Rmpfr_add($r1, $r1, $r1, $rnd),
where $r1 *is* the same reference to the same mpfr structure,
would add $r1 to itself and store the result in $r1. Alternatively,
you could (courtesy of operator overloading) simply code it
as $r1 += $r1. Otoh, Rmpfr_add($r1, $r2, $r3, $rnd), where each of the
arguments is a different reference to a different mpfr structure
would add $r2 to $r3 and store the result in $r1. Alternatively
it could be coded as $r1 = $r2 + $r3.

"$ui" means any integer that will fit into a C 'unsigned long int',

"$si" means any integer that will fit into a C 'signed long int'.

"$sj" means any integer that will fit into a C 'intmax_t'. Don't
use any of these functions unless your perl was compiled with 64
bit support.

"$double" is a C double and "$float" is a C float ... but both will
be represented in Perl as an NV.

"$bool" means a value (usually a 'signed long int') in which
the only interest is whether it evaluates as false or true.

"$str" simply means a string of symbols that represent a number,
eg '1234567890987654321234567@7' which might be a base 10 number,
or 'zsa34760sdfgq123r5@11' which would have to represent at least
a base 36 number (because "z" is a valid digit only in bases 36
and above). Valid bases for MPFR numbers are 0 and 2 to 36 (2 to 62
if Math::MPFR has been built against mpfr-3.0.0 or later).

"$rnd" is simply one of the 4 rounding mode values (discussed above).

"$p" is the (signed int) value for precision.

##############

ROUNDING MODES

Rmpfr_set_default_rounding_mode($rnd);
 Sets the default rounding mode to $rnd.
 The default rounding mode is to nearest initially (GMP_RNDN).
 The default rounding mode is the rounding mode that
 is used in overloaded operations.

$si = Rmpfr_get_default_rounding_mode();
 Returns the numeric value (0, 1, 2 or 3) of the
 current default rounding mode. This will initially be 0.

$si = Rmpfr_prec_round($rop, $p, $rnd); 
 Rounds $rop according to $rnd with precision $p, which may be
 different from that of $rop.  If $p is greater or equal to the
 precision of $rop, then new space is allocated for the mantissa,
 and it is filled with zeroes.  Otherwise, the mantissa is rounded
 to precision $p with the given direction. In both cases, the
 precision of $rop is changed to $p.  The returned value is zero
 when the result is exact, positive when it is greater than the
 original value of $rop, and negative when it is smaller.  The
 precision $p can be any integer between RMPFR_PREC_MIN and
 RMPFR_PREC_MAX.  

##########

EXCEPTIONS

$si =  Rmpfr_get_emin();
$si =  Rmpfr_get_emax();
 Return the (current) smallest and largest exponents
 allowed for a floating-point variable.

$si = Rmpfr_get_emin_min();
$si = Rmpfr_get_emin_max();
$si = Rmpfr_get_emax_min();
$si = Rmpfr_get_emax_max();
 Return the minimum and maximum of the smallest and largest
 exponents allowed for `mpfr_set_emin' and `mpfr_set_emax'. These
 values are implementation dependent

$bool =  Rmpfr_set_emin($si);
$bool =  Rmpfr_set_emax($si);
 Set the smallest and largest exponents allowed for a
 floating-point variable.  Return a non-zero value when $si is not
 in the range of exponents accepted by the implementation (in that
 case the smallest or largest exponent is not changed), and zero
 otherwise. If the user changes the exponent range, it is her/his
 responsibility to check that all current floating-point variables
 are in the new allowed range (for example using `Rmpfr_check_range',
 otherwise the subsequent behaviour will be undefined, in the sense
 of the ISO C standard. 

$si2 = Rmpfr_check_range($op, $si1, $rnd);
 This function has changed from earlier implementations.
 It now forces $op to be in the current range of acceptable
 values, $si1 the current ternary value: negative if $op is
 smaller than the exact value, positive if $op is larger than the
 exact value and zero if $op is exact (before the call). It generates
 an underflow or an overflow if the exponent of $op is outside the
 current allowed range; the value of $si1 may be used to avoid a
 double rounding. This function returns zero if the rounded result
 is equal to the exact one, a positive value if the rounded result
 is larger than the exact one, a negative value if the rounded
 result is smaller than the exact one. Note that unlike most
 functions, the result is compared to the exact one, not the input
 value $op, i.e. the ternary value is propagated.
 Note: If $op is an infinity and $si1 is different from zero
 (i.e., if the rounded result is an inexact infinity), then the
 overflow flag is set.

Rmpfr_set_underflow();
Rmpfr_set_overflow();
Rmpfr_set_nanflag();
Rmpfr_set_inexflag();
Rmpfr_set_erangeflag();
Rmpfr_clear_underflow();
Rmpfr_clear_overflow();
Rmpfr_clear_nanflag();
Rmpfr_clear_inexflag();
Rmpfr_clear_erangeflag();
 Set/clear the underflow, overflow, invalid, inexact and erange flags.

Rmpfr_clear_flags();
 Clear all global flags (underflow, overflow, inexact, invalid,
 and erange).

$bool = Rmpfr_underflow_p();
$bool = Rmpfr_overflow_p();
$bool = Rmpfr_nanflag_p();
$bool = Rmpfr_inexflag_p();
$bool = Rmpfr_erangeflag_p();
 Return the corresponding (underflow, overflow, invalid, inexact
 or erange) flag, which is non-zero iff the flag is set.

$si = Rmpfr_subnormalize ($op, $si, $rnd);
 See the MPFR documentation for mpfr_subnormalize().

##############

INITIALIZATION

A variable should be initialized once only.

First read the section 'MEMORY MANAGEMENT' (above).

Rmpfr_set_default_prec($p);
 Set the default precision to be *exactly* $p bits.  The
 precision of a variable means the number of bits used to store its
 mantissa.  All subsequent calls to `mpfr_init' will use this
 precision, but previously initialized variables are unaffected.
 This default precision is set to 53 bits initially.  The precision
 can be any integer between RMPFR_PREC_MIN and RMPFR_PREC_MAX.

$ui = Rmpfr_get_default_prec();
 Returns the default MPFR precision in bits.

$rop = Math::MPFR->new();
$rop = Math::MPFR::new();
$rop = new Math::MPFR();
$rop = Rmpfr_init();
$rop = Rmpfr_init_nobless();
 Initialize $rop, and set its value to NaN. The precision 
 of $rop is the default precision, which can be changed
 by a call to `Rmpfr_set_default_prec'.

$rop = Rmpfr_init2($p);
$rop = Rmpfr_init2_nobless($p);
 Initialize $rop, set its precision to be *exactly* $p bits,
 and set its value to NaN.  To change the precision of a
 variable which has already been initialized,
 use `Rmpfr_set_prec' instead.  The precision $p can be
 any integer between RMPFR_PREC_MIN and RMPFR_PREC_MAX.

@rops = Rmpfr_inits($how_many);
@rops = Rmpfr_inits_nobless($how_many);
 Returns an array of $how_many Math::MPFR objects - initialized,
 with a value of NaN, and with default precision.
 (These functions do not wrap mpfr_inits.)

@rops = Rmpfr_inits2($p, $how_many);
@rops = Rmpfr_inits2_nobless($p, $how_many);
 Returns an array of $how_many Math::MPFR objects - initialized,
 with a value of NaN, and with precision of $p.
 (These functions do not wrap mpfr_inits2.)
 

Rmpfr_set_prec($op, $p);
 Reset the precision of $op to be *exactly* $p bits.
 The previous value stored in $op is lost.  The precision
 $p can be any integer between RMPFR_PREC_MIN and
 RMPFR_PREC_MAX. If you want to keep the previous
 value stored in $op, use 'Rmpfr_prec_round' instead.

$si = Rmpfr_get_prec($op);
 Return the precision actually used for assignments of $op,
i.e. the number of bits used to store its mantissa.

Rmpfr_set_prec_raw($rop, $p);
 Reset the precision of $rop to be *exactly* $p bits.  The only
 difference with `mpfr_set_prec' is that $p is assumed to be small
 enough so that the mantissa fits into the current allocated
 memory space for $rop. Otherwise an error will occur.

$min_prec = Rmpfr_min_prec($op);
 $min_prec is set to the minimal number of bits required to store
 the significand of $op, and 0 for special values, including 0.
(Warning: the returned value can be less than RMPFR_PREC_MIN.)

$minimum_precision = RMPFR_PREC_MIN;
$maximum_precision = RMPFR_PREC_MAX;
 Returns the minimum/maximum precision for Math::MPFR objects
 allowed by the mpfr library being used.

##########

ASSIGNMENT

$si = Rmpfr_set($rop, $op, $rnd);
$si = Rmpfr_set_ui($rop, $ui, $rnd);
$si = Rmpfr_set_si($rop, $si, $rnd);
$si = Rmpfr_set_sj($rop, $sj, $rnd); # 64 bit
$si = Rmpfr_set_uj($rop, $uj, $rnd); # 64 bit
$si = Rmpfr_set_d($rop, $double, $rnd);
$si = Rmpfr_set_ld($rop, $ld, $rnd); # long double
$si = Rmpfr_set_z($rop, $z, $rnd); # $z is a mpz object.
$si = Rmpfr_set_q($rop, $q, $rnd); # $q is a mpq object.
$si = Rmpfr_set_f($rop, $f, $rnd); # $f is a mpf object.
$si = Rmpfr_set_flt($rop, $float, $rnd); # mpfr-3.0.0 and later only
 Set the value of $rop from 2nd arg, rounded to the precision of
 $rop towards the given direction $rnd.  Please note that even a 
 'long int' may have to be rounded if the destination precision
 is less than the machine word width.  The return value is zero
 when $rop=2nd arg, positive when $rop>2nd arg, and negative when 
 $rop<2nd arg.  For `mpfr_set_d', be careful that the input
 number $double may not be exactly representable as a double-precision
 number (this happens for 0.1 for instance), in which case it is
 first rounded by the C compiler to a double-precision number,
 and then only to a mpfr floating-point number.

$si = Rmpfr_set_ui_2exp($rop, $ui, $exp, $rnd);
$si = Rmpfr_set_si_2exp($rop, $si, $exp, $rnd);
$si = Rmpfr_set_uj_2exp($rop, $sj, $exp, $rnd); # 64 bit
$si = Rmpfr_set_sj_2exp($rop, $sj, $exp, $rnd); # 64 bit
$si = Rmpfr_set_z_2exp($rop, $z, $exp, $rnd); # mpfr-3.0.0 and later only
 Set the value of $rop from the 2nd arg multiplied by two to the
 power $exp, rounded towards the given direction $rnd.  Note that
 the input 0 is converted to +0. ($z is a GMP mpz object.)

$si = Rmpfr_set_str($rop, $str, $base, $rnd);
 Set $rop to the value of $str in base $base (0,2..36 or, if
 Math::MPFR has been built against mpfr-3.0.0 or later, 0,2..62),
 rounded in direction $rnd to the precision of $rop. 
 The exponent is read in decimal.  This function returns 0 if
 the entire string is a valid number in base $base. otherwise
 it returns -1. If $base is zero, the base is set according to 
 the following rules:
  if the string starts with '0b' or '0B' the base is set to 2;
  if the string starts with '0x' or '0X' the base is set to 16;
  otherwise the base is set to 10.
 The following exponent symbols can be used:
  '@' - can be used for any base;
  'e' or 'E' - can be used only with bases <= 10;
  'p' or 'P' - can be used to introduce binary exponents with
               hexadecimal or binary strings.
 See the MPFR library documentation for more details. See also
 'Rmpfr_inp_str' (below). 
 Because of the special significance of the '@' symbol in perl,
 make sure you assign to strings using single quotes, not
 double quotes, when using '@' as the exponent marker. If you 
 must use double quotes (which is hard to believe) then you
 need to escape the '@'. ie the following two assignments are
 equivalent:
  Rmpfr_set_str($rop, '.1234@-5', 10, GMP_RNDN);
  Rmpfr_set_str($rop, ".1234\@-5", 10, GMP_RNDN);
 But the following assignment won't do what you want:
  Rmpfr_set_str($rop, ".1234@-5", 10, GMP_RNDN); 

Rmpfr_strtofr($rop, $str, $base, $rnd);
 Read a floating point number from a string $str in base $base,
 rounded in the direction $rnd. If successful, the result is
 stored in $rop. If $str doesn't start with a valid number then
 $rop is set to zero.
 Parsing follows the standard C `strtod' function with some
 extensions.  Case is ignored. After optional leading whitespace,
 one has a subject sequence consisting of an optional sign (`+' or
 `-'), and either numeric data or special data. The subject
 sequence is defined as the longest initial subsequence of the
 input string, starting with the first non-whitespace character,
 that is of the expected form.
 The form of numeric data is a non-empty sequence of significand
 digits with an optional decimal point, and an optional exponent
 consisting of an exponent prefix followed by an optional sign and
 a non-empty sequence of decimal digits. A significand digit is
 either a decimal digit or a Latin letter (62 possible characters),
 with `a' = 10, `b' = 11, ..., `z' = 36; its value must be strictly
 less than the base.  The decimal point can be either the one
 defined by the current locale or the period (the first one is
 accepted for consistency with the C standard and the practice, the
 second one is accepted to allow the programmer to provide MPFR
 numbers from strings in a way that does not depend on the current
 locale).  The exponent prefix can be `e' or `E' for bases up to
 10, or `@' in any base; it indicates a multiplication by a power
 of the base. In bases 2 and 16, the exponent prefix can also be
 `p' or `P', in which case it introduces a binary exponent: it
 indicates a multiplication by a power of 2 (there is a difference
 only for base 16).  The value of an exponent is always written in
 base 10.  In base 2, the significand can start with `0b' or `0B',
 and in base 16, it can start with `0x' or `0X'.

 If the argument $base is 0, then the base is automatically detected
 as follows. If the significand starts with `0b' or `0B', base 2 is
 assumed. If the significand starts with `0x' or `0X', base 16 is
 assumed. Otherwise base 10 is assumed. Other allowable values for 
 $base are 2 to 36 (2 to 62 if Math::MPFR has been built against
 mpfr-3.0.0 or later).

 Note: The exponent must contain at least a digit. Otherwise the
 possible exponent prefix and sign are not part of the number
 (which ends with the significand). Similarly, if `0b', `0B', `0x'
 or `0X' is not followed by a binary/hexadecimal digit, then the
 subject sequence stops at the character `0'.
 Special data (for infinities and NaN) can be `@inf@' or
 `@nan@(n-char-sequence)', and if BASE <= 16, it can also be
 `infinity', `inf', `nan' or `nan(n-char-sequence)', all case
 insensitive.  A `n-char-sequence' is a non-empty string containing
 only digits, Latin letters and the underscore (0, 1, 2, ..., 9, a,
 b, ..., z, A, B, ..., Z, _). Note: one has an optional sign for
 all data, even NaN.
 The function returns a usual ternary value.

Rmpfr_set_str_binary($rop, $str);
 Set $rop to the value of the binary number in $str, which has to
 be of the form +/-xxxx.xxxxxxEyy. The exponent is read in decimal,
 but is interpreted as the power of two to be multiplied by the
 mantissa.  The mantissa length of $str has to be less or equal to
 the precision of $rop, otherwise an error occurs.  If $str starts
 with `N', it is interpreted as NaN (Not-a-Number); if it starts
 with `I' after the sign, it is interpreted as infinity, with the
 corresponding sign.

Rmpfr_set_inf($rop, $si);
Rmpfr_set_nan($rop);
Rmpfr_set_zero($rop, $si); # mpfr-3.0.0 and later only.
 Set the variable $rop to infinity or NaN (Not-a-Number) or zero
 respectively. In 'mpfr_set_inf' and 'mpfr_set_zero', the sign of $rop
 is positive if 2nd arg >= 0. Else the sign is negative.

Rmpfr_swap($op1, $op2); 
 Swap the values $op1 and $op2 efficiently. Warning: the precisions
 are exchanged too; in case the precisions are different, `mpfr_swap'
 is thus not equivalent to three `mpfr_set' calls using a third
 auxiliary variable.

################################################

COMBINED INITIALIZATION AND ASSIGNMENT

NOTE: Do NOT use these functions if $rop has already
been initialised. Use the Rmpfr_set* functions in the
section 'ASSIGNMENT' (above).

First read the section 'MEMORY MANAGEMENT' (above).

$rop = Math::MPFR->new($arg);
$rop = Math::MPFR::new($arg);
$rop = new Math::MPFR($arg);
 Returns a Math::MPFR object with the value of $arg, rounded
 in the default rounding direction, with default precision.
 $arg can be either a number (signed integer, unsigned integer,
 signed fraction or unsigned fraction), a string that 
 represents a numeric value, or an object (of type Math::GMPf,
 Math::GMPq, Math::GMPz, orMath::GMP) If $arg is a string, an
 optional additional argument that specifies the base of the
 number can be supplied to new(). Legal values for base are 0
 and 2 to 36 (2 to 62 if Math::MPFR has been built against
 mpfr-3.0.0 or later). If $arg is a string and no 
 additional argument is supplied, an attempt is made to deduce 
 base. See 'Rmpfr_set_str' above for an explanation of how
 that deduction is attempted. For finer grained control, use
 one of the 'Rmpfr_init_set_*' functions documented immediately
 below.

($rop, $si) = Rmpfr_init_set($op, $rnd);
($rop, $si) = Rmpfr_init_set_nobless($op, $rnd);
($rop, $si) = Rmpfr_init_set_ui($ui, $rnd);
($rop, $si) = Rmpfr_init_set_ui_nobless($ui, $rnd);
($rop, $si) = Rmpfr_init_set_si($si, $rnd);
($rop, $si) = Rmpfr_init_set_si_nobless($si, $rnd);
($rop, $si) = Rmpfr_init_set_d($double, $rnd);
($rop, $si) = Rmpfr_init_set_d_nobless($double, $rnd);
($rop, $si) = Rmpfr_init_set_ld($double, $rnd);
($rop, $si) = Rmpfr_init_set_ld_nobless($double, $rnd);
($rop, $si) = Rmpfr_init_set_f($f, $rnd);# $f is a mpf object
($rop, $si) = Rmpfr_init_set_f_nobless($f, $rnd);# $f is a mpf object
($rop, $si) = Rmpfr_init_set_z($z, $rnd);# $z is a mpz object
($rop, $si) = Rmpfr_init_set_z_nobless($z, $rnd);# $z is a mpz object
($rop, $si) = Rmpfr_init_set_q($q, $rnd);# $q is a mpq object
($rop, $si) = Rmpfr_init_set_q_nobless($q, $rnd);# $q is a mpq object
 Initialize $rop and set its value from the 1st arg, rounded to
 direction $rnd. The precision of $rop will be taken from the
 active default precision, as set by `Rmpfr_set_default_prec'.
 If $rop = 1st arg, $si is zero. If $rop > 1st arg, $si is positive.
 If $rop < 1st arg, $si is negative.

($rop, $si) = Rmpfr_init_set_str($str, $base, $rnd);
($rop, $si) = Rmpfr_init_set_str_nobless($str, $base, $rnd);
  Initialize $rop and set its value from $str in base $base,
  rounded to direction $rnd. If $str was a valid number, then
  $si will be set to 0. Else it will be set to -1.
  See `Rmpfr_set_str' (above) and 'Rmpfr_inp_str' (below).

##########

CONVERSION

$str = Rmpfr_get_str($op, $base, $digits, $rnd); 
 Returns a string of the form, eg, '8.3456712@2'
 which means '834.56712'.
 The third argument to Rmpfr_get_str() specifies the number of digits
 required to be output in the mantissa. (Trailing zeroes are removed.)
 If $digits is 0, the number of digits of the mantissa is chosen
 large enough so that re-reading the printed value with the same
 precision, assuming both output and input use rounding to nearest,
 will recover the original value of $op.

($str, $si) = Rmpfr_deref2($op, $base, $digits, $rnd);
 Returns the mantissa to $str (as a string of digits, prefixed with
 a minus sign if $op is negative), and returns the exponent to $si.
 There's an implicit decimal point to the left of the first digit in
 $str. The third argument to Rmpfr_deref2() specifies the number of
 digits required to be output in the mantissa. 
 If $digits is 0, the number of digits of the mantissa is chosen
 large enough so that re-reading the printed value with the same
 precision, assuming both output and input use rounding to nearest,
 will recover the original value of $op.

$str = Rmpfr_integer_string($op, $base, $rnd);
 Returns the truncated integer value of $op as a string. (No exponent
 is returned). For example, if $op contains the value 2.3145679e2,
 $str will be set to "231".
 (This function is mainly to provide a simple means of getting 'sj'
 and 'uj' values on a 64-bit perl where the MPFR library does not
 support mpfr_get_uj and mpfr_get_sj functions - which may happen,
 for example, with libraries built with Microsoft Compilers.)

$bool = Rmpfr_fits_ushort_p($op, $rnd); # fits in unsigned long
$bool = Rmpfr_fits_sshort_p($op, $rnd); # fits in signed long
$bool = Rmpfr_fits_uint_p($op, $rnd); # fits in unsigned long
$bool = Rmpfr_fits_sint_p($op, $rnd); # fits in signed long
$bool = Rmpfr_fits_ulong_p($op, $rnd); # fits in unsigned long
$bool = Rmpfr_fits_slong_p($op, $rnd); # fits in signed long
$bool = Rmpfr_fits_uintmax_p($op, $rnd); # fits in unsigned long
$bool = Rmpfr_fits_intmax_p($op, $rnd); # fits in signed long
$bool = Rmpfr_fits_IV_p($op, $rnd); # fits in perl IV
$bool = Rmpfr_fits_UV_p($op, $rnd); # fits in perl UV
 Return non-zero if $op would fit in the respective data
 type, when rounded to an integer in the direction $rnd.

$ui = Rmpfr_get_ui($op, $rnd); 
$si = Rmpfr_get_si($op, $rnd);
$sj = Rmpfr_get_sj($op, $rnd); # 64 bit builds only
$uj = Rmpfr_get_uj($op, $rnd); # 64 bit builds only
$uv = Rmpfr_get_UV($op, $rnd); # 32 and 64 bit
$iv = Rmpfr_get_IV($op, $rnd); # 32 and 64 bit
 Convert $op to an 'unsigned long long', a 'signed long', a
'signed long long', an `unsigned long long', a 'UV', or an
'IV' - after rounding it with respect to $rnd.
 If $op is NaN, the result is undefined. If $op is too big
 for the return type, it returns the maximum or the minimum
 of the corresponding C type, depending on the direction of
 the overflow. The flag erange is then also set.

$double = Rmpfr_get_d($op, $rnd);
$ld     = Rmpfr_get_ld($op, $rnd);
$nv     = Rmpfr_get_NV($op, $rnd);
$float  = Rmpfr_get_flt($op, $rnd); # mpfr-3.0.0 and later only
 Convert $op to a 'double' a 'long double' an 'NV', or a float
 using the rounding mode $rnd. (I don't know how perl can do
 anything useful with Rmpfr_get_flt.)

$double = Rmpfr_get_d1($op);
 Convert $op to a double, using the default MPFR rounding mode
 (see function `mpfr_set_default_rounding_mode').

$si = Rmpfr_get_z_exp($z, $op); # $z is a mpz object
$si = Rmpfr_get_z_2exp($z, $op); # $z is a mpz object
 (Identical functions. Use either - 'get_z_exp' might one day
 be removed.)
 Puts the mantissa of $rop into $z, and returns the exponent 
 $si such that $rop == $z * (2 ** $ui).

$si = Rmpfr_get_z($z, $op, $rnd); # $z is a mpz object.
 Convert $op to an mpz object ($z), after rounding it with respect
 to RND. If built against mpfr-3.0.0 or later, return the usual
 ternary value. (The function returns undef when using mpfr-2.x.x.)
 If $op is NaN or Inf, the result is undefined.

$si = Rmpfr_get_f ($f, $op, $rnd); # $f is an mpf object.
 Convert $op to a `mpf_t', after rounding it with respect to $rnd.
 When built against mpfr-3.0.0 or later, this function returns the
 usual ternary value. (If $op is NaN or Inf, then the erange flag
 will be set.) When built against earlier versions of mpfr,
 return zero iff no error occurred.In particular a non-zero value
 is returned if $op is NaN or Inf. which do not exist in `mpf'.

$d = Rmpfr_get_d_2exp ($exp, $op, $rnd); # $d is NV (double)
$d = Rmpfr_get_ld_2exp ($exp, $op, $rnd); # $d is NV (long double)
 Set $exp and $d such that 0.5<=abs($d)<1 and $d times 2 raised
 to $exp equals $op rounded to double (resp. long double)
 precision, using the given rounding mode.  If $op is zero, then a
 zero of the same sign (or an unsigned zero, if the implementation
 does not have signed zeros) is returned, and $exp is set to 0.
 If $op is NaN or an infinity, then the corresponding double
 precision (resp. long-double precision) value is returned, and 
 $exp is undefined.

##########

ARITHMETIC

$si = Rmpfr_add($rop, $op1, $op2, $rnd);
$si = Rmpfr_add_ui($rop, $op, $ui, $rnd);
$si = Rmpfr_add_si($rop, $op, $si1, $rnd);
$si = Rmpfr_add_d($rop, $op, $double, $rnd);
$si = Rmpfr_add_z($rop, $op, $z, $rnd); # $z is a mpz object.
$si = Rmpfr_add_q($rop, $op, $q, $rnd); # $q is a mpq object.
 Set $rop to 2nd arg + 3rd arg rounded in the direction $rnd.
 The return  value is zero if $rop is exactly 2nd arg + 3rd arg,
 positive if $rop is larger than 2nd arg + 3rd arg, and negative
 if $rop is smaller than 2nd arg + 3rd arg.

$si = Rmpfr_sum($rop, \@ops, scalar(@ops), $rnd);
 @ops is an array consisting entirely of Math::MPFR objects.
 Set $rop to the sum of all members of @ops, rounded in the direction
 $rnd. $si is zero when the computed value is the exact value, and
 non-zero when this cannot be guaranteed, without giving the direction
 of the error as the other functions do. 

$si = Rmpfr_sub($rop, $op1, $op2, $rnd);
$si = Rmpfr_sub_ui($rop, $op, $ui, $rnd);
$si = Rmpfr_sub_z($rop, $op, $z, $rnd); # $z is a mpz object.
$si = Rmpfr_sub_q($rop, $op, $q, $rnd); # $q is a mpq object.
$si = Rmpfr_ui_sub($rop, $ui, $op, $rnd);
$si = Rmpfr_si_sub($rop, $si1, $op, $rnd);
$si = Rmpfr_sub_si($rop, $op, $si1, $rnd);
$si = Rmpfr_sub_d($rop, $op, $double, $rnd);
$si = Rmpfr_d_sub($rop, $double, $op, $rnd);
 Set $rop to 2nd arg - 3rd arg rounded in the direction $rnd.
 The return value is zero if $rop is exactly 2nd arg - 3rd arg,
 positive if $rop is larger than 2nd arg - 3rd arg, and negative
 if $rop is smaller than 2nd arg - 3rd arg.

$si = Rmpfr_mul($rop, $op1, $op2, $rnd);
$si = Rmpfr_mul_ui($rop, $op, $ui, $rnd);
$si = Rmpfr_mul_si($rop, $op, $si1, $rnd);
$si = Rmpfr_mul_d($rop, $op, $double, $rnd);
$si = Rmpfr_mul_z($rop, $op, $z, $rnd); # $z is a mpz object.
$si = Rmpfr_mul_q($rop, $op, $q, $rnd); # $q is a mpq object.
 Set $rop to 2nd arg * 3rd arg rounded in the direction $rnd.
 Return 0 if the result is exact, a positive value if $rop is 
 greater than 2nd arg times 3rd arg, a negative value otherwise.

$si = Rmpfr_div($rop, $op1, $op2, $rnd);
$si = Rmpfr_div_ui($rop, $op, $ui, $rnd);
$si = Rmpfr_ui_div($rop, $ui, $op, $rnd);
$si = Rmpfr_div_si($rop, $op, $si1, $rnd);
$si = Rmpfr_si_div($rop, $si1, $op, $rnd);
$si = Rmpfr_div_d($rop, $op, $double, $rnd);
$si = Rmpfr_d_div($rop, $double, $op, $rnd);
$si = Rmpfr_div_z($rop, $op, $z, $rnd); # $z is a mpz object.
$si = Rmpfr_div_q($rop, $op, $q, $rnd); # $q is a mpq object.
 Set $rop to 2nd arg / 3rd arg rounded in the direction $rnd. 
 These functions return 0 if the division is exact, a positive
 value when $rop is larger than 2nd arg divided by 3rd arg,
 and a negative value otherwise.

$si = Rmpfr_sqr($rop, $op, $rnd);
 Set $rop to the square of $op, rounded in direction $rnd.

$si = Rmpfr_sqrt($rop, $op, $rnd);
$si = Rmpfr_sqrt_ui($rop, $ui, $rnd);
 Set $rop to the square root of the 2nd arg rounded in the
 direction $rnd. Set $rop to NaN if 2nd arg is negative.
 Return 0 if the operation is exact, a non-zero value otherwise.

$si = Rmpfr_rec_sqrt($rop, $op, $rnd);
 Set $rop to the reciprocal square root of $op rounded in the
 direction $rnd. Return +Inf if OP is ±0, and +0 if OP is +Inf.
 Set $rop to NaN if $op is negative.

$si = Rmpfr_cbrt($rop, $op, $rnd);
 Set $rop to the cubic root (defined over the real numbers)
 of $op, rounded in the direction $rnd.

$si = Rmpfr_root($rop, $op, $ui $rnd);
 Set $rop to the $ui'th root of $op, rounded in the direction
 $rnd.  Return 0 if the operation is exact, a non-zero value
 otherwise.

$si = Rmpfr_pow_ui($rop, $op, $ui, $rnd);
$si = Rmpfr_pow_si($rop, $op, $si, $rnd);
$si = Rmpfr_ui_pow_ui($rop, $ui, $ui, $rnd);
$si = Rmpfr_ui_pow($rop, $ui, $op, $rnd);
$si = Rmpfr_pow($rop, $op1, $op2, $rnd);
$si = Rmpfr_pow_z($rop, $op1, $z, $rnd); # $z is a mpz object
 Set $rop to 2nd arg raised to 3rd arg, rounded to the directio
 $rnd with the precision of $rop.  Return zero iff the result is
 exact, a positive value when the result is greater than 2nd arg
 to the power 3rd arg, and a negative value when it is smaller.
 See the MPFR documentation for documentation regarding special 
 cases.

$si = Rmpfr_neg($rop, $op, $rnd);
 Set $rop to -$op rounded in the direction $rnd. Just
 changes the sign if $rop and $op are the same variable.

$si = Rmpfr_abs($rop, $op, $rnd);
 Set $rop to the absolute value of $op, rounded in the direction
 $rnd. Return 0 if the result is exact, a positive value if ROP
 is larger than the absolute value of $op, and a negative value 
 otherwise.

$si = Rmpfr_dim($rop, $op1, $op2, $rnd);
 Set $rop to the positive difference of $op1 and $op2, i.e.,
 $op1 - $op2 rounded in the direction $rnd if $op1 > $op2, and
 +0 otherwise. $rop is set to NaN when $op1 or $op2 is NaN.

$si = Rmpfr_mul_2exp($rop, $op, $ui, $rnd);
$si = Rmpfr_mul_2ui($rop, $op, $ui, $rnd);
$si = Rmpfr_mul_2si($rop, $op, $si, $rnd);
 Set $rop to 2nd arg times 2 raised to 3rd arg rounded to the
 direction $rnd. Just increases the exponent by 3rd arg when
 $rop and 2nd arg are identical. Return zero when $rop = 2nd
 arg, a positive value when $rop > 2nd arg, and a negative
 value when $rop < 2nd arg.  Note: The `Rmpfr_mul_2exp' function
 is defined for compatibility reasons; you should use
 `Rmpfr_mul_2ui' (or `Rmpfr_mul_2si') instead.

$si = Rmpfr_div_2exp($rop, $op, $ui, $rnd);
$si = Rmpfr_div_2ui($rop, $op, $ui, $rnd);
$si = Rmpfr_div_2si($rop, $op, $si, $rnd);
 Set $rop to 2nd arg divided by 2 raised to 3rd arg rounded to
 the direction $rnd. Just decreases the exponent by 3rd arg
 when $rop and 2nd arg are identical.  Return zero when 
 $rop = 2nd arg, a positive value when $rop > 2nd arg, and a
 negative value when $rop < 2nd arg.  Note: The `Rmpfr_div_2exp'
 function is defined for compatibility reasons; you should
 use `Rmpfr_div_2ui' (or `Rmpfr_div_2si') instead.

##########
  
COMPARISON

$si = Rmpfr_cmp($op1, $op2);
$si = Rmpfr_cmpabs($op1, $op2);
$si = Rmpfr_cmp_ui($op, $ui);
$si = Rmpfr_cmp_si($op, $si);
$si = Rmpfr_cmp_d($op, $double);
$si = Rmpfr_cmp_ld($op, $ld); # long double
$si = Rmpfr_cmp_z($op, $z); # $z is a mpz object
$si = Rmpfr_cmp_q($op, $q); # $q is a mpq object
$si = Rmpfr_cmp_f($op, $f); # $f is a mpf object
 Compare 1st and 2nd args. In the case of 'Rmpfr_cmpabs()'
 compare the absolute values of the 2 args.  Return a positive
 value if 1st arg > 2nd arg, zero if 1st arg = 2nd arg, and a 
 negative value if 1st arg < 2nd arg.  Both args are considered
 to their full own precision, which may differ. In case 1st and 
 2nd args are of same sign but different, the absolute value 
 returned is one plus the absolute difference of their exponents.
 If one of the operands is NaN (Not-a-Number), return zero 
 and set the erange flag.


$si = Rmpfr_cmp_ui_2exp($op, $ui, $si);
$si = Rmpfr_cmp_si_2exp($op, $si, $si);
 Compare 1st arg and 2nd arg multiplied by two to the power 
 3rd arg.

$bool = Rmpfr_eq($op1, $op2, $ui);
 The mpfr library function mpfr_eq may change in future 
 releases of the mpfr library (post 2.4.0). If that happens,
 the change will also be relected in Rmpfr_eq.
 Return non-zero if the first $ui bits of $op1 and $op2 are
 equal, zero otherwise.  I.e., tests if $op1 and $op2 are 
 approximately equal.

$bool = Rmpfr_nan_p($op);
 Return non-zero if $op is Not-a-Number (NaN), zero otherwise.

$bool = Rmpfr_inf_p($op);
 Return non-zero if $op is plus or minus infinity, zero otherwise.

$bool = Rmpfr_number_p($op);
 Return non-zero if $op is an ordinary number, i.e. neither
 Not-a-Number nor plus or minus infinity.

$bool = Rmpfr_zero_p($op);
 Return non-zero if $op is zero. Else return 0.

$bool = Rmpfr_regular_p($op); # mpfr-3.0.0 and later only
 Return non-zero if $op is a regular number (i.e. neither NaN,
 nor an infinity nor zero). Return zero otherwise.

Rmpfr_reldiff($rop, $op1, $op2, $rnd);
 Compute the relative difference between $op1 and $op2 and 
 store the result in $rop.  This function does not guarantee
 the exact rounding on the relative difference; it just
 computes abs($op1-$op2)/$op1, using the rounding mode
 $rnd for all operations.

$si = Rmpfr_sgn($op);
 Return a positive value if op > 0, zero if $op = 0, and a
 negative value if $op < 0.  Its result is not specified
 when $op is NaN (Not-a-Number).

$bool = Rmpfr_greater_p($op1, $op2);
 Return non-zero if $op1 > $op2, zero otherwise.

$bool = Rmpfr_greaterequal_p($op1, $op2);
 Return non-zero if $op1 >= $op2, zero otherwise.

$bool = Rmpfr_less_p($op1, $op2);
 Return non-zero if $op1 < $op2, zero otherwise.

$bool = Rmpfr_lessequal_p($op1, $op2);
 Return non-zero if $op1 <= $op2, zero otherwise.

$bool = Rmpfr_lessgreater_p($op1, $op2);
 Return non-zero if $op1 < $op2 or $op1 > $op2 (i.e. neither
 $op1, nor $op2 is NaN, and $op1 <> $op2), zero otherwise
 (i.e. $op1 and/or $op2 are NaN, or $op1 = $op2).

$bool = Rmpfr_equal_p($op1, $op2);
 Return non-zero if $op1 = $op2, zero otherwise
 (i.e. $op1 and/or $op2 are NaN, or $op1 <> $op2).

$bool = Rmpfr_unordered_p($op1, $op2);
  Return non-zero if $op1 or $op2 is a NaN
  (i.e. they cannot be compared), zero otherwise.

#######

SPECIAL

$si = Rmpfr_log($rop, $op, $rnd);
$si = Rmpfr_log2($rop, $op, $rnd);
$si = Rmpfr_log10($rop, $op, $rnd);
 Set $rop to the natural logarithm of $op, log2($op) or 
 log10($op), respectively, rounded in the direction rnd.

$si = Rmpfr_exp($rop, $op, $rnd);
$si = Rmpfr_exp2($rop, $op, $rnd);
$si = Rmpfr_exp10($rop, $op, $rnd);
 Set rop to the exponential of op, to 2 power of op or to
 10 power of op, respectively, rounded in the direction rnd. 

$si = Rmpfr_sin($rop $op, $rnd);
$si = Rmpfr_cos($rop, $op, $rnd);
$si = Rmpfr_tan($rop, $op, $rnd);
 Set $rop to the sine/cosine/tangent respectively of $op,
 rounded to the direction $rnd with the precision of $rop.
 Return 0 iff the result is exact (this occurs in fact only
 when $op is 0 i.e. the sine is 0, the cosine is 1, and the
 tangent is 0). Return a negative value iff the result is less
 than the actual value. Return a positive result iff the
 return is greater than the actual value.

$si = Rmpfr_sin_cos($rop1, $rop2, $op, $rnd);
 Set simultaneously $rop1 to the sine of $op and
 $rop2 to the cosine of $op, rounded to the direction $rnd
 with their corresponding precisions.  Return 0 iff both
 results are exact.

$si = Rmpfr_sinh_cosh($rop1, $rop2, $op, $rnd);
 Set simultaneously $rop1SOP to the hyperbolic sine of $op and
 $rop2 to the hyperbolic cosine of $op, rounded in the direction
 $rnd with the corresponding precision of $rop1 and $rop2 which
 must be different variables. Return 0 iff both results are
 exact.

$si = Rmpfr_acos($rop, $op, $rnd);
$si = Rmpfr_asin($rop, $op, $rnd);
$si = Rmpfr_atan($rop, $op, $rnd);
 Set $rop to the arc-cosine, arc-sine or arc-tangent of $op,
 rounded to the direction $rnd with the precision of $rop.
 Return 0 iff the result is exact. Return a negative value iff
 the result is less than the actual value. Return a positive 
 result iff the return is greater than the actual value.

$si = Rmpfr_atan2($rop, $op1, $op2, $rnd);
 Set $rop to the tangent of $op1/$op2, rounded to the 
 direction $rnd with the precision of $rop.
 Return 0 iff the result is exact. Return a negative value iff
 the result is less than the actual value. Return a positive 
 result iff the return is greater than the actual value.
 See the MPFR documentation for details regarding special cases.   


$si = Rmpfr_cosh($rop, $op, $rnd);
$si = Rmpfr_sinh($rop, $op, $rnd);
$si = Rmpfr_tanh($rop, $op, $rnd);
 Set $rop to the hyperbolic cosine/hyperbolic sine/hyperbolic
 tangent respectively of $op, rounded to the direction $rnd
 with the precision of $rop.  Return 0 iff the result is exact
 (this occurs in fact only when OP is 0 i.e. the result is 1).
 Return a negative value iff the result is less than the actual
 value. Return a positive result iff the return is greater than
 the actual value.

$si = Rmpfr_acosh($rop, $op, $rnd);
$si = Rmpfr_asinh($rop, $op, $rnd);
$si = Rmpfr_atanh($rop, $op, $rnd);
 Set $rop to the inverse hyperbolic cosine, sine or tangent
 of $op, rounded to the direction $rnd with the precision of
 $rop.  Return 0 iff the result is exact.

$si = Rmpfr_sec ($rop, $op, $rnd);
$si = Rmpfr_csc ($rop, $op, $rnd);
$si = Rmpfr_cot ($rop, $op, $rnd);
 Set $rop to the secant of $op, cosecant of $op,
 cotangent of $op, rounded in the direction RND. Return 0 
 iff the result is exact. Return a negative value iff the
 result is less than the actual value. Return a positive 
 result iff the return is greater than the actual value.

$si = Rmpfr_sech ($rop, $op, $rnd);
$si = Rmpfr_csch ($rop, $op, $rnd);
$si = Rmpfr_coth ($rop, $op, $rnd);
 Set $rop to the hyperbolic secant of $op, cosecant of $op,
 cotangent of $op, rounded in the direction RND. Return 0 
 iff the result is exact. Return a negative value iff the
 result is less than the actual value. Return a positive 
 result iff the return is greater than the actual value.

$bool = Rmpfr_fac_ui($rop, $ui, $rnd);
 Set $rop to the factorial of $ui, rounded to the direction
 $rnd with the precision of $rop.  Return 0 iff the
 result is exact.

$bool = Rmpfr_log1p($rop, $op, $rnd);
 Set $rop to the logarithm of one plus $op, rounded to the
 direction $rnd with the precision of $rop.  Return 0 iff 
 the result is exact (this occurs in fact only when OP is 0
 i.e. the result is 0).

$bool = Rmpfr_expm1($rop, $op, $rnd);
 Set $rop to the exponential of $op minus one, rounded to the
 direction $rnd with the precision of $rop.  Return 0 iff the
 result is exact (this occurs in fact only when OP is 0 i.e
 the result is 0).

$si = Rmpfr_fma($rop, $op1, $op2, $op3, $rnd);
 Set $rop to $op1 * $op2 + $op3, rounded to the direction
 $rnd.

$si = Rmpfr_fms($rop, $op1, $op2, $op3, $rnd);
 Set $rop to $op1 * $op2 - $op3, rounded to the direction
 $rnd.

$si = Rmpfr_agm($rop, $op1, $op2, $rnd);
 Set $rop to the arithmetic-geometric mean of $op1 and $op2,
 rounded to the direction $rnd with the precision of $rop.
 Return zero if $rop is exact, a positive value if $rop is
 larger than the exact value, or a negative value if $rop 
 is less than the exact value.

$si = Rmpfr_hypot ($rop, $op1, $op2, $rnd);
 Set $rop to the Euclidean norm of $op1 and $op2, i.e. the 
 square root of the sum of the squares of $op1 and $op2, 
 rounded in the direction $rnd. Special values are currently
 handled as described in Section F.9.4.3 of the ISO C99 
 standard, for the hypot function (note this may change in 
 future versions): If $op1 or $op2 is an infinity, then plus
 infinity is returned in $rop, even if the other number is
 NaN.

$si = Rmpfr_ai($rop, $op, $rnd); # mpfr-3.0.0 and later only
 Set $rop to the value of the Airy function Ai on $op,
 rounded in the direction $rnd.  When $op is NaN, $rop is
 always set to NaN. When $op is +Inf or -Inf, $rop is +0.
 The current implementation is not intended to be used with
 large arguments.  It works with $op typically smaller than
 500. For larger arguments, other methods should be used and
 will be implemented soon.


$si = Rmpfr_const_log2($rop, $rnd);
 Set $rop to the logarithm of 2 rounded to the direction
 $rnd with the precision of $rop. This function stores the
 computed value to avoid another calculation if a lower or
 equal precision is requested.
 Return zero if $rop is exact, a positive value if $rop is
 larger than the exact value, or a negative value if $rop 
 is less than the exact value.

$si = Rmpfr_const_pi($rop, $rnd);
 Set $rop to the value of Pi rounded to the direction $rnd
 with the precision of $rop. This function uses the Borwein,
 Borwein, Plouffe formula which directly gives the expansion
 of Pi in base 16.
 Return zero if $rop is exact, a positive value if $rop is
 larger than the exact value, or a negative value if $rop 
 is less than the exact value.

$si = Rmpfr_const_euler($rop, $rnd);
 Set $rop to the value of Euler's constant 0.577...  rounded
 to the direction $rnd with the precision of $rop.
 Return zero if $rop is exact, a positive value if $rop is
 larger than the exact value, or a negative value if $rop 
 is less than the exact value.

$si = Rmpfr_const_catalan($rop, $rnd);
 Set $rop to the value of Catalan's constant 0.915...
 rounded to the direction $rnd with the precision of $rop.
 Return zero if $rop is exact, a positive value if $rop is
 larger than the exact value, or a negative value if $rop 
 is less than the exact value.

Rmpfr_free_cache();
 Free the cache used by the functions computing constants if
 needed (currently `mpfr_const_log2', `mpfr_const_pi' and
 `mpfr_const_euler').

$si = Rmpfr_gamma($rop, $op, $rnd);
$si = Rmpfr_lngamma($rop, $op, $rnd);
 Set $rop to the value of the Gamma function on $op 
(and, respectively, its natural logarithm) rounded
 to the direction $rnd. Return zero if $rop is exact, a
 positive value if $rop is larger than the exact value, or a
 negative value if $rop is less than the exact value.

($signp, $si) = Rmpfr_lgamma ($rop, $op, $rnd);
 Set $rop to the value of the logarithm of the absolute value
 of the Gamma function on $op, rounded in the direction $rnd.
 The sign (1 or -1) of Gamma($op) is returned in $signp.
 When $op is an infinity or a non-positive integer, +Inf is
 returned. When $op is NaN, -Inf or a negative integer, $signp
 is undefined, and when OP is ±0, $signp is the sign of the zero.

$si = Rmpfr_digamma ($rop, $op, $rnd); # mpfr-3.0.0 and later only
 Set $rop to the value of the Digamma (sometimes also called Psi)
 function on $op, rounded in the direction $rnd.  When $op is a
 negative integer, set $rop to NaN.

$si = Rmpfr_zeta($rop, $op, $rnd);
$si = Rmpfr_zeta_ui($rop, $ul, $rnd);
 Set $rop to the value of the Riemann Zeta function on 2nd arg,
 rounded to the direction $rnd. Return zero if $rop is exact,
 a positive value if $rop is larger than the exact value, or
 a negative value if $rop is less than the exact value.

$si = Rmpfr_erf($rop, $op, $rnd);
 Set $rop to the value of the error function on $op,
 rounded to the direction $rnd. Return zero if $rop is exact,
 a positive value if $rop is larger than the exact value, or
 a negative value if $rop is less than the exact value.

$si = Rmpfr_erfc($rop, $op, $rnd);
 Set $rop to the complementary error function on $op,
 rounded to the direction $rnd. Return zero if $rop is exact,
 a positive value if $rop is larger than the exact value, or
 a negative value if $rop is less than the exact value.

$si = Rmpfr_j0 ($rop, $op, $rnd);
$si = Rmpfr_j1 ($rop, $op, $rnd);
$si = Rmpfr_jn ($rop, $si2, $op, $rnd);
 Set $rop to the value of the first order Bessel function of
 order 0, 1 and $si2 on $op, rounded in the direction $rnd.
 When $op is NaN, $rop is always set to NaN. When $op is plus
 or minus Infinity, $rop is set to +0. When $op is zero, and
 $si2 is not zero, $rop is +0 or -0 depending on the parity 
 and sign of $si2, and the sign of $op.

$si = Rmpfr_y0 ($rop, $op, $rnd);
$si = Rmpfr_y1 ($rop, $op, $rnd);
$si = Rmpfr_yn ($rop, $si2, $op, $rnd);
  Set $rop to the value of the second order Bessel function of
  order 0, 1 and $si2 on OP, rounded in the direction $rnd.
  When $op is NaN or negative, $rop is always set to NaN.
  When $op is +Inf, $rop is +0. When $op is zero, $rop is +Inf
  or -Inf depending on the parity and sign of $si2.

$si = Rmpfr_eint ($rop, $op, $rnd)
  Set $rop to the exponential integral of $op, rounded in the
  direction $rnd. See the MPFR documentation for details.

$si = Rmpfr_li2 ($rop, $op, $rnd);
 Set $rop to real part of the dilogarithm of $op, rounded in the
 direction $rnd. The dilogarithm function is defined here as
 the integral of -log(1-t)/t from 0 to x.

#############

I-O FUNCTIONS

$ui = Rmpfr_out_str([$prefix,] $op, $base, $digits, $round [, $suffix]);
 BEST TO USE TRmpfr_out_str INSTEAD
 Output $op to STDOUT, as a string of digits in base $base,
 rounded in direction $round.  The base may vary from 2 to 36
 (2 to 62 if Math::MPFR has been built against mpfr-3.0.0 or later).
 Print $digits significant digits exactly, or if $digits is 0,
 enough digits so that $op can be read back exactly
 (see Rmpfr_get_str). In addition to the significant
 digits, a decimal point at the right of the first digit and a
 trailing exponent in base 10, in the form `eNNN', are printed
 If $base is greater than 10, `@' will be used instead of `e'
 as exponent delimiter. The optional arguments, $prefix and 
 $suffix, are strings that will be prepended/appended to the 
 mpfr_out_str output. Return the number of bytes written (not
 counting those contained in $suffix and $prefix), or if an error
 occurred, return 0. (Note that none, one or both of $prefix and
 $suffix can be supplied.)

$ui = TRmpfr_out_str([$prefix,] $stream, $base, $digits, $op, $round [, $suffix]);
 As for Rmpfr_out_str, except that there's the capability to print
 to somewhere other than STDOUT. Note that the order of the args
 is different (to match the order of the mpfr_out_str args).
 To print to STDERR:
    TRmpfr_out_str(*stderr, $base, $digits, $op, $round);
 To print to an open filehandle (let's call it FH):
    TRmpfr_out_str(\*FH, $base, $digits, $op, $round);

$ui = Rmpfr_inp_str($rop, $base, $round);
 BEST TO USE TRmpfr_inp_str INSTEAD.
 Input a string in base $base from STDIN, rounded in
 direction $round, and put the read float in $rop.  The string
 is of the form `M@N' or, if the base is 10 or less, alternatively
 `MeN' or `MEN', or, if the base is 16, alternatively `MpB' or
 `MPB'. `M' is the mantissa in the specified base, `N' is the 
 exponent written in decimal for the specified base, and in base 16,
 `B' is the binary exponent written in decimal (i.e. it indicates
 the power of 2 by which the mantissa is to be scaled).
 The argument $base may be in the range 2 to 36 (2 to 62 if Math::MPFR
 has been built against mpfr-3.0.0 or later).
 Special values can be read as follows (the case does not matter):
 `@NaN@', `@Inf@', `+@Inf@' and `-@Inf@', possibly followed by
 other characters; if the base is smaller or equal to 16, the
 following strings are accepted too: `NaN', `Inf', `+Inf' and
 `-Inf'.
 Return the number of bytes read, or if an error occurred, return 0.

$ui = TRmpfr_inp_str($rop, $stream, $base, $round);
 As for Rmpfr_inp_str, except that there's the capability to read
 from somewhere other than STDIN.
 To read from STDIN:
    TRmpfr_inp_str($rop, *stdin, $base, $round);
 To read from an open filehandle (let's call it FH):
    TRmpfr_inp_str($rop, \*FH, $base,  $round);

Rmpfr_print_binary($op);
 Output $op on stdout in raw binary format (the exponent is in
 decimal, yet).

Rmpfr_dump($op);
 Output "$op\n" on stdout in base 2.
 As with 'Rmpfr_print_binary' the exponent is in base 10.

#############

MISCELLANEOUS

$MPFR_version = Rmpfr_get_version();
 Returns the version of the MPFR library (eg 2.1.0) being used by
 Math::MPFR.

$GMP_version = Math::MPFR::gmp_v();
 Returns the version of the gmp library (eg. 4.1.3) being used by
 the mpfr library that's being used by Math::MPFR.
 The function is not exportable.

$ui = MPFR_VERSION;
 An integer whose value is dependent upon the 'major', 'minor' and
 'patchlevel' values of the MPFR library against which Math::MPFR 
 was built.
 This value is from the mpfr.h that was in use when the compilation
 of Math::MPFR took place.

$ui = MPFR_VERSION_MAJOR;
 The 'x' in the 'x.y.z' of the MPFR library version.
 This value is from the mpfr.h that was in use when the compilation
 of Math::MPFR took place.

$ui = MPFR_VERSION_MINOR;
 The 'y' in the 'x.y.z' of the MPFR library version.
 This value is from the mpfr.h that was in use when the compilation
 of Math::MPFR took place.

$ui = MPFR_VERSION_PATCHLEVEL;
 The 'z' in the 'x.y.z' of the MPFR library version.
 This value is from the mpfr.h that was in use when the compilation
 of Math::MPFR took place.

$string = MPFR_VERSION_STRING;
 $string is set to the version of the MPFR library (eg 2.1.0)
 against which Math::MPFR was built.
 This value is from the mpfr.h that was in use when the compilation
 of Math::MPFR took place.

$ui = MPFR_VERSION_NUM($major, $minor, $patchlevel);
 Returns the value for MPFR_VERSION on "MPFR-$major.$minor.$patchlevel".

$str = Rmpfr_get_patches();
 Return a string containing the ids of the patches applied to the
 MPFR library (contents of the `PATCHES' file), separated by spaces.
 Note: If the program has been compiled with an older MPFR version and
 is dynamically linked with a new MPFR library version, the ids of the
 patches applied to the old (compile-time) MPFR version are not 
 available (however this information should not have much interest
 in general).

$bool = Rmpfr_buildopt_tls_p(); # mpfr-3.0.0 and later only
 Return a non-zero value if mpfr was compiled as thread safe using
 compiler-level Thread Local Storage (that is mpfr was built with
 the `--enable-thread-safe' configure option, return zero otherwise.

$bool = Rmpfr_buildopt_decimal_p(); # mpfr-3.0.0 and later only
 Return a non-zero value if mpfr was compiled with decimal float
 support (that is mpfr was built with the `--enable-decimal-float'
 configure option), return zero otherwise.

$si = Rmpfr_rint($rop, $op, $rnd);
$si = Rmpfr_ceil($rop, $op);
$si = Rmpfr_floor($rop, $op);
$si = Rmpfr_round($rop, $op);
$si = Rmpfr_trunc($rop, $op);
 Set $rop to $op rounded to an integer. `Rmpfr_ceil' rounds to the
 next higher representable integer, `Rmpfr_floor' to the next lower,
 `Rmpfr_round' to the nearest representable integer, rounding
 halfway cases away from zero, and `Rmpfr_trunc' to the
 representable integer towards zero. `Rmpfr_rint' behaves like one
 of these four functions, depending on the rounding mode.  The
 returned value is zero when the result is exact, positive when it
 is greater than the original value of $op, and negative when it is
 smaller.  More precisely, the returned value is 0 when $op is an
 integer representable in $rop, 1 or -1 when $op is an integer that
 is not representable in $rop, 2 or -2 when $op is not an integer.

 $si = Rmpfr_rint_ceil($rop, $op, $rnd);
 $si = Rmpfr_rint_floor($rop, $op, $rnd);
 $si = Rmpfr_rint_round($rop, $op, $rnd);
 $si = Rmpfr_rint_trunc($rop, $op, $rnd):
  Set $rop to $op rounded to an integer. `Rmpfr_rint_ceil' rounds to
  the next higher or equal integer, `Rmpfr_rint_floor' to the next
  lower or equal integer, `Rmpfr_rint_round' to the nearest integer,
  rounding halfway cases away from zero, and `Rmpfr_rint_trunc' to
  the next integer towards zero.  If the result is not
  representable, it is rounded in the direction $rnd. The returned
  value is the ternary value associated with the considered
  round-to-integer function (regarded in the same way as any other
  mathematical function).

$si = Rmpfr_frac($rop, $op, $round);
 Set $rop to the fractional part of OP, having the same sign as $op,
 rounded in the direction $round (unlike in `mpfr_rint', $round
 affects only how the exact fractional part is rounded, not how
 the fractional part is generated).

$si = Rmpfr_modf ($rop1, $rop2, $op, $rnd);
 Set simultaneously $rop1 to the integral part of $op and $rop2
 to the fractional part of $op, rounded in the direction RND with
 the corresponding precision of $rop1 and $rop2 (equivalent to
 `Rmpfr_trunc($rop1, $op, $rnd)' and `Rmpfr_frac($rop1, $op, $rnd)').
 The variables $rop1 and $rop2 must be different. Return 0 iff both
 results are exact.

$si = Rmpfr_remainder($rop, $op1, $op2, $rnd);
$si = Rmpfr_fmod($rop, $op1, $op2, $rnd);
($si2, $si) = Rmpfr_remquo ($rop, $op1, $op2, $rnd);
 Set $rop to the remainder of the division of $op1 by $op2, with
 quotient rounded toward zero for 'Rmpfr_fmod' and to the nearest
 integer (ties rounded to even) for 'Rmpfr_remainder' and 
 'Rmpfr_remquo', and $rop rounded according to the direction $rnd.
 Special values are handled as described in Section F.9.7.1 of the
 ISO C99 standard: If $op1 is infinite or $op2 is zero, $rop is NaN.
 If $op2 is infinite and $op1 is finite, $rop is $op1 rounded to
 the precision of $rop. If $rop is zero, it has the sign of $op1.
 The return value is the ternary value corresponding to $rop.
 Additionally, `Rmpfr_remquo' stores the low significant bits from
 the quotient in $si2 (more precisely the number of bits in a `long'
 minus one), with the sign of $op1 divided by $op2 (except if those
 low bits are all zero, in which case zero is returned).  Note that
 $op1 may be so large in magnitude relative to $op2 that an exact
 representation of the quotient is not practical.  `Rmpfr_remainder'
 and `Rmpfr_remquo' functions are useful for additive argument
 reduction.

$si = Rmpfr_integer_p($op);
 Return non-zero iff $op is an integer.

Rmpfr_nexttoward($op1, $op2);
 If $op1 or $op2 is NaN, set $op1 to NaN. Otherwise, if $op1 is 
 different from $op2, replace $op1 by the next floating-point number
 (with the precision of $op1 and the current exponent range) in the 
 direction of $op2, if there is one (the infinite values are seen as
 the smallest and largest floating-point numbers). If the result is
 zero, it keeps the same sign. No underflow or overflow is generated.

Rmpfr_nextabove($op1);
 Equivalent to `mpfr_nexttoward' where $op2 is plus infinity.

Rmpfr_nextbelow($op1);
 Equivalent to `mpfr_nexttoward' where $op2 is minus infinity.

$si = Rmpfr_min($rop, $op1, $op2, $round);
 Set $rop to the minimum of $op1 and $op2. If $op1 and $op2
 are both NaN, then $rop is set to NaN. If $op1 or $op2 is 
 NaN, then $rop is set to the numeric value. If $op1 and
 $op2 are zeros of different signs, then $rop is set to -0.

$si = Rmpfr_max($rop, $op1, $op2, $round);
  Set $rop to the maximum of $op1 and $op2. If $op1 and $op2
 are both NaN, then $rop is set to NaN. If $op1 or $op2 is
 NaN, then $rop is set to the numeric value. If $op1 and 
 $op2 are zeros of different signs, then $rop is set to +0.

##############

RANDOM NUMBERS

Rmpfr_urandomb(@r, $state);
 Requires that one of Math::GMPz, Math::GMPq or Math::GMPf
 is loaded.
 Each member of @r is a Math::MPFR object.
 $state is a reference to a gmp_randstate_t structure.
 Set each member of @r to a uniformly distributed random
 float in the interval 0 <= $_ < 1. 
 Before using this function you must first create $state
 by calling one of the 3 Rgmp_randinit functions, then
 seed $state by calling one of the 2 Rgmp_randseed functions.
 The memory associated with $state will not be freed until
 either you call Rgmp_randclear, or the program ends.

Rmpfr_random2($rop, $si, $ui); # not implemented in
                               # mpfr-3.0.0 and later
 Attempting to use this function when Math::MPFR has been
 built against mpfr-3.0.0 will cause the program to die, with
 an appropriate error message.
 Generate a random float of at most abs($si) limbs, with long
 strings of zeros and ones in the binary representation.
 The exponent of the number is in the interval -$ui to
 $ui.  This function is useful for testing functions and
 algorithms, since this kind of random numbers have proven
 to be more likely to trigger corner-case bugs.  Negative
 random numbers are generated when $si is negative.

$si = Rmpfr_urandom ($rop, $state, $rnd); # mpfr-3.0.0 and
                                          # later only
 Requires that one of Math::GMPz, Math::GMPq or Math::GMPf
 is loaded.
 Generate a uniformly distributed random float.  The
 floating-point number $rop can be seen as if a random real
 number is generated according to the continuous uniform
 distribution on the interval[0, 1] and then rounded in the
 direction RND.
 Before using this function you must first create $state by 
 calling one of the 3 Rgmp_randinit functions (below).

$state = Rgmp_randinit_default();
 Requires that one of Math::GMPz, Math::GMPq or Math::GMPf
 is loaded.
 Initialise $state with a default algorithm. This will be
 a compromise between speed and randomness, and is 
 recommended for applications with no special requirements.
 (This GMP function is documented in the Math::GMP* module
 that was loaded)

$state = Rgmp_randinit_lc_2exp($a, $c, $m2exp);
 Requires that one of Math::GMPz, Math::GMPq or Math::GMPf
 is loaded.
 This function is not tested in the test suite.
 Use with caution - I often select values here that cause
 Rmpf_urandomb() to behave non-randomly.    
 Initialise $state with a linear congruential algorithm:
 X = ($a * X + $c) % 2 ** $m2exp
 The low bits in X are not very random - for this reason
 only the high half of each X is actually used.
 $c and $m2exp sre both unsigned longs.
 $a can be any one of Math::GMP, or Math::GMPz objects.
 Or it can be a string.
 If it is a string of hex digits it must be prefixed with
 either OX or Ox. If it is a string of octal digits it must
 be prefixed with 'O'. Else it is assumed to be a decimal
 integer. No other bases are allowed.
 (This GMP function is documented in the Math::GMP* module
 that was loaded)

$state = Rgmp_randinit_lc_2exp_size($ui);
 Initialise state as per Rgmp_randinit_lc_2exp. The values
 for $a, $c. and $m2exp are selected from a table, chosen
 so that $ui bits (or more) of each X will be used.
 (This GMP function is documented in the Math::GMP* module
 that was loaded)

Rgmp_randseed($state, $seed);
 Requires that one of Math::GMPz, Math::GMPq or Math::GMPf
 is loaded.
 $state is a reference to a gmp_randstate_t strucure (the
 return value of one of the Rgmp_randinit functions).
 $seed is the seed. It can be any one of Math::GMP, 
 or Math::GMPz objects. Or it can be a string.
 If it is a string of hex digits it must be prefixed with
 either OX or Ox. If it is a string of octal digits it must
 be prefixed with 'O'. Else it is assumed to be a decimal
 integer. No other bases are allowed.
 (This GMP function is documented in the Math::GMP* module
 that was loaded)

Rgmp_randseed_ui($state, $ui);
 Requires that one of Math::GMPz, Math::GMPq or Math::GMPf
 is loaded.
 $state is a reference to a gmp_randstate_t strucure (the
 return value of one of the Rgmp_randinit functions).
 $ui is the seed.
 (This GMP function is documented in the Math::GMP* module
 that was loaded)

#########

INTERNALS

$bool = Rmpfr_can_round($op, $ui, $rnd1, $rnd2, $p);
 Assuming $op is an approximation of an unknown number X in direction
 $rnd1 with error at most two to the power E(b)-$ui where E(b) is
 the exponent of $op, returns 1 if one is able to round exactly X
 to precision $p with direction $rnd2, and 0 otherwise. This
 function *does not modify* its arguments.

$si = Rmpfr_get_exp($op);
 Get the exponent of $op, assuming that $op is a non-zero
 ordinary number.

$si = Rmpfr_set_exp($op, $si);
 Set the exponent of $op if $si is in the current exponent 
 range, and return 0 (even if $op is not a non-zero
 ordinary number); otherwise, return a non-zero value.

$si = Rmpfr_signbit ($op);
 Return a non-zero value iff $op has its sign bit set (i.e. if it is
 negative, -0, or a NaN whose representation has its sign bit set).

$si2 = Rmpfr_setsign ($rop, $op, $si, $rnd);
 Set the value of $rop from $op, rounded towards the given direction
 $rnd, then set/clear its sign bit if $si is true/false (even when
 $op is a NaN).

$si = Rmpfr_copysign ($rop, $op1, $op2, $rnd);
 Set the value of $rop from $op1, rounded towards the given direction
 $rnd, then set its sign bit to that of $op2 (even when $op1 or $op2
 is a NaN). This function is equivalent to:
 Rmpfr_setsign ($rop, $op1, Rmpfr_signbit ($op2), $rnd)'.

####################

OPERATOR OVERLOADING

 Overloading works with numbers, strings (bases 2, 10, and 16
 only - see step '4.' below) and Math::MPFR objects.
 Overloaded operations are performed using the current
 "default rounding mode" (which you can determine using the
 'Rmpfr_get_default_rounding_mode' function, and change using
 the 'Rmpfr_set_default_rounding_mode' function).

 Be aware that when you use overloading with a string operand,
 the overload subroutine converts that string operand to a
 Math::MPFR object with *current default precision*, and using
 the *current default rounding mode*.

 Note that any comparison using the spaceship operator ( <=> )
 will return undef iff either/both of the operands is a NaN.
 All comparisons ( < <= > >= == != <=> ) involving one or more
 NaNs will set the erange flag.

 For the purposes of the overloaded 'not', '!' and 'bool'
 operators, a "false" Math::MPFR object is one whose value is
 either 0 (including -0) or NaN.
 (A "true" Math::MPFR object is, of course, simply one that
 is not "false".)

 The following operators are overloaded:
  + - * / ** sqrt (Return object has default precision)
  += -= *= /= **= (Precision remains unchanged)
  < <= > >= == != <=>
  ! not bool
  abs atan2 cos sin log exp (Return object has default precision)
  int (On perl 5.8 only, NA on perl 5.6. The return object
       has default precision)
  = (The copy has the same precision as the copied object.)
  ""

 Attempting to use the overloaded operators with objects that
 have been blessed into some package other than 'Math::MPFR'
 will not (currently) work. It would be fun (and is tempting)
 to implement cross-class overloading - but it could also
 easily lead to user confusion and frustration, so I'll resist
 the temptation until someone convinces me that I should do
 otherwise.
 The workaround is to convert this "foreign" object to a
 format that *will* work with the overloaded operator.

 In those situations where the overload subroutine operates on 2
 perl variables, then obviously one of those perl variables is
 a Math::MPFR object. To determine the value of the other variable
 the subroutine works through the following steps (in order),
 using the first value it finds, or croaking if it gets
 to step 6:

 1. If the variable is an unsigned long then that value is used.
    The variable is considered to be an unsigned long if 
    (perl 5.8) the UOK flag is set or if (perl 5.6) SvIsUV() 
    returns true.(In the case of perls built with
    -Duse64bitint, the variable is treated as an unsigned long
    long int if the UOK flag is set.)

 2. If the variable is a signed long int, then that value is used.
    The variable is considered to be a signed long int if the
    IOK flag is set. (In the case of perls built with
    -Duse64bitint, the variable is treated as a signed long long
    int if the IOK flag is set.)

 3. If the variable is a double, then that value is used. The
    variable is considered to be a double if the NOK flag is set.
    (In the case of perls built with -Duselongdouble, the variable
    is treated as a long double if the NOK flag is set.)

 4. If the variable is a string (ie the POK flag is set) then the
    value of that string is used. If the POK flag is set, but the
    string is not a valid number, the subroutine croaks with an 
    appropriate error message. If the string starts with '0b' or
    '0B' it is regarded as a base 2 number. If it starts with '0x'
    or '0X' it is regarded as a base 16 number. Otherwise it is
    regarded as a base 10 number.

 5. If the variable is a Math::MPFR object then the value of that
    object is used.

 6. If none of the above is true, then the second variable is
    deemed to be of an invalid type. The subroutine croaks with
    an appropriate error message.

#####################

FORMATTED OUTPUT

Rmpfr_printf($format_string, [$rnd,] $var);

 This function (unlike the MPFR counterpart) is limited to taking
 2 or 3 arguments - the format string, optionally a rounding argument,
 and the variable to be formatted.
 That is, you can currently printf only one variable at a time.
 If there's no variable to be formatted, just add a '0' as the final
 argument. ie this will work fine:
  Rmpfr_printf("hello world\n", 0);
 See the mpfr documentation for details re the formatting options.
 Note: Courtesy of operator overloading, you can also use perl's
 printf() function with Math::MPFR objects.

Rmpfr_fprintf($fh, $format_string, [$rnd,] $var);

 This function (unlike the MPFR counterpart) is limited to taking
 3 or 4 arguments - the filehandle, the format string, optionally a
 rounding argument, and the variable to be formatted. That is, you
 can printf only one variable at a time.
 If there's no variable to be formatted, just add a '0' as the final
 argument. ie this will work fine:
  Rmpfr_fprintf($fh, "hello world\n", 0);
 See the mpfr documentation for details re the formatting options.

Rmpfr_sprintf($buffer, $format_string, [$rnd,] $var);

 This function (unlike the MPFR counterpart) is limited to taking
 3 or 4 arguments - the buffer, the format string, optionally a
 rounding argument, and the variable to be formatted. $buffer must be
 large enough to accommodate the formatted string, and is truncated
 to the length of that formatted string. If you prefer to have the
 resultant string returned (rather than stored in $buffer), use
 Rmpfrf_sprintf_ret instead - which will also leave the length of
 $buffer unaltered. 
 If there's no variable to be formatted, just add a '0' as the final
 argument. ie this will work fine:
  Rmpfr_sprintf($buffer, "hello world", 0);
 See the mpfr documentation for details re the formatting options.
 Note: Courtesy of operator overloading, you can also use perl's
 sprintf() function with Math::MPFR objects.

$string = Rmpfr_sprintf_ret($buffer, $format_string, [$rnd,] $var);

 As for Rmpfr_sprintf, but returns the formatted string, rather than
 storing it in $buffer. $buffer needs to be large enough to 
 accommodate the formatted string. The length of $buffer will be
 unaltered.
 See the mpfr documentation for details re the formatting options.
 Note: Courtesy of operator overloading, you can also use perl's
 sprintf() function with Math::MPFR objects.

Rmpfr_snprintf($buffer, $bytes, $format_string, [$rnd,] $var);

 This function (unlike the MPFR counterpart) is limited to taking
 4 or 5 arguments - the buffer, the number of bytes to be written,
 the format string, optionally a rounding argument, and the variable
 to be formatted. $buffer must be large enough to accommodate the 
 formatted string, and is truncated to the length of that formatted
 string. If you prefer to have the resultant string returned (rather
 than stored in $buffer), use Rmpfrf_sprintf_ret instead - which will
 also leave the length of $buffer unaltered. 
 If there's no variable to be formatted, just add a '0' as the final
 argument. ie this will work fine:
  Rmpfr_snprintf($buffer, 12, "hello world", 0);
 See the mpfr documentation for further details.

$string = Rmpfr_snprintf_ret($buffer, $bytes, $format_string, [$rnd,] $var);

 As for Rmpfr_snprintf, but returns the formatted string, rather than
 storing it in $buffer. $buffer needs to be large enough to 
 accommodate the formatted string. The length of $buffer will be
 unaltered.

#####################

BUGS

You can get segfaults if you pass the wrong type of
argument to the functions - so if you get a segfault, the
first thing to do is to check that the argument types 
you have supplied are appropriate.

ACKNOWLEDGEMENTS

Thanks to Vincent Lefevre for providing corrections to errors
and omissions, and suggesting improvements (which were duly
put in place).

LICENSE

This program is free software; you may redistribute it and/or 
modify it under the same terms as Perl itself.
Copyright 2006-2008, 2009, 2010, 2011 Sisyphus

AUTHOR

Sisyphus <sisyphus at(@) cpan dot (.) org>

1 POD Error

The following errors were encountered while parsing the POD:

Around line 1317:

Non-ASCII character seen before =encoding in '±0,'. Assuming CP1252