/ 
Math-NV-0.01
River stage one • 1 direct dependent • 1 total dependent
/ Math::NV

NAME

Math::NV - assign correct value to perl's NV

DESCRIPTION

use Math::NV qw(:all);
my $nv = nv('1e-298'); # ie the number 10 ** -298

The above snippet will assign a correct value for 1e-298 to $nv.
Doing simply "$nv = 1e-298;" may *not* do that. (The test suite
specifically checks and reports whether 1e-298 can correctly be
assigned directly to a perl scalar. It also checks some other
values).

The nv() function assigns the value at the C (XS) level using
either the C function strtod() or strtold() - whichever is 
appropriate for your perl's configuration.

Obviously, we are therefore relying upon absence of bugs in the
way your compiler/libc assigns strings to floats. (Hopefully, if
such bugs are present, this will become evident in the form of
failures in the module's test suite.)

FUNCTIONS

$nv = nv($str);

 On perls whose NV is a C "double", assigns to $nv the value that
 the C standard library function strtod($str) assigns.
 On perls whose NV is a C "long double", assigns to $nv the value
 that the C standard library function strtold($str) assigns.

$nv_type = nv_type();

 Returns either "double" or "long double", depending upon the way
 perl has been configured.
 The expectation is that it returns the same as $Config{nvtype}.
 (Please file a bug report if you find otherwise.)

$digits = mant_dig();

 Returns the number of bits the NV mantissa contains. This is
 normally 53 if nv_type() is double - otherwise usually (but by no
 means always) 64.
 It returns the value of the C macro DBL_MANT_DIG or LDBL_MANT_DIG,
 depending upon whichever is appropriate for perl's configuration.

($mantissa, $exponent, $precision) = ld2binary($nv, $flag);

 Returns a base 2 representation of the long double value contained
 in the NV $nv.
 If $flag is true, it also prints out additional information during
 calculation.
 $mantissa is the mantissa (significand).
 $exponent is the exponent.
 $precision is the precision (in bits) of the mantissa - trailing
 zero bits are not counted.
 For doubles, use Data::Float's float_hex($nv) - which also works
 for long double NV's on most architectures (but not powerpc).

($mantissa, $exponent, $precision) = ld_str2binary($str, $flag);

 Returns a base 2 representation of the long double value
 represented by the string $str.
 If $flag is true, it also prints out additional information during
 calculation.
 $mantissa is the mantissa (significand).
 $exponent is the exponent.
 $precision is the precision (in bits) of the mantissa - trailing
 zero bits are not counted.
 For doubles, use Data::Float's float_hex($str) - which also works
 for long double NV's on most architectures (but not powerpc).

LICENSE

This program is free software; you may redistribute it and/or modify
it under the same terms as Perl itself.
Copyright 2013 Sisyphus

AUTHOR

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