/ 
POSIX-1003-0.95.1
River stage one • 2 direct dependents • 2 total dependents
/ POSIX::1003::Math

NAME

POSIX::1003::Math - POSIX handling time

SYNOPSIS

use POSIX::1003::Math qw/ceil floor sqrt/;
print ceil 3.14;
print sqrt floor 4.9;

DESCRIPTION

Be aware that math in Perl has unclear precission! Be aware that the math library often provides many variations of these functions... it is hard to determine which one is used. Probably, Math::Trig will serve you better. Or PDL for real number crunchers.

Be warned that these functions do not have an obligatory scalar parameter, but only an optional parameter (defaults to $_). This means that they have the lowest (is list) priority.

FUNCTIONS

Standard POSIX via this module (via POSIX.xs)

Like the built-in sin, cos, and sqrt, the EXPR defaults to $_ and there is a scalar context (missing from POSIX.pm).

acos(EXPR)
asin(EXPR)
atan(EXPR)
ceil(EXPR)
cosh(EXPR)
div(NUMER, DENOM)

Devide NUMER by DENOminator. The result is a list of two: quotient and remainder. Implemented in Perl for completeness, currently not with the speed of XS.

my ($quotient, $remainder) = div($number, $denom);
floor(EXPR)
fmod(EXPR, EXPR)
frexp(EXPR)
ldexp(EXPR)
log10(EXPR)
modf(EXPR, EXPR)
pow(EXPR1, EXPR2)

Returns EXPR1 ** EXPR2

rint(NUMBER)

Round to the closest integer. Implemented in Perl for completeness.

sinh(EXPR)
tan(EXPR)
tanh(EXPR)

Standard POSIX, using CORE

A small set of mathematical functions are available in Perl CORE, without the need to load this module. But if you do import them, it simply gets ignored.

abs([EXPR])
atan2(EXPR, EXPR)
cos([EXPR])
exp([EXPR])
log([EXPR])
rand([EXPR])
sin([EXPR])
sqrt([EXPR])
srand([EXPR])

Numeric conversions

All strto*, atof, atoi and friends functions are usually not needed in Perl programs: the integer and float types are at their largest size, so when a string is used in numeric context it will get converted automatically. Still, POSIX.xs does provide a few of those functions, which are sometimes more accurate in number parsing for large numbers.

All three provided functions treat errors the same way. Truly POSIX-compliant systems set $ERRNO ($!) to indicate a translation error, so clear $! before calling strto*. Non-compliant systems may not check for overflow, and therefore will never set $!.

To parse a string $str as a floating point number use

$! = 0;
($num, $n_unparsed) = strtod($str);

if($str eq '' || $n_unparsed != 0 || $!) {
    die "Non-numeric input $str" . ($! ? ": $!\n" : "\n");
}

# When you do not care about handling errors, you can do
$num = strtod($str);
$num = $str + 0;     # same: Perl auto-converts
strtod(STRING)

String to double translation. Returns the parsed number and the number of characters in the unparsed portion of the string. When called in a scalar context strtod returns the parsed number.

strtol(STRING, BASE)

String to integer translation. Returns the parsed number and the number of characters in the unparsed portion of the string. When called in a scalar context strtol returns the parsed number.

The base should be zero or between 2 and 36, inclusive. When the base is zero or omitted strtol will use the string itself to determine the base: a leading "0x" or "0X" means hexadecimal; a leading "0" means octal; any other leading characters mean decimal. Thus, "1234" is parsed as a decimal number, "01234" as an octal number, and "0x1234" as a hexadecimal number.

strtoul(STRING, BASE)

String to unsigned integer translation, which behaves like strtol.

CONSTANTS

The following constants are exported, shown here with the values discovered during installation of this module:

CHAR_BIT         8
CHAR_MAX         127
CHAR_MIN         -128
DBL_DIG          15
DBL_EPSILON      2.22044604925031e-16
DBL_MANT_DIG     53
DBL_MAX          1.79769313486232e+308
DBL_MAX_10_EXP   308
DBL_MAX_EXP      1024
DBL_MIN          2.2250738585072e-308
DBL_MIN_10_EXP   -307
DBL_MIN_EXP      -1021
FLT_DIG          6
FLT_EPSILON      1.19209289550781e-07
FLT_MANT_DIG     24
FLT_MAX          3.40282346638529e+38
FLT_MAX_10_EXP   38
FLT_MAX_EXP      128
FLT_MIN          1.17549435082229e-38
FLT_MIN_10_EXP   -37
FLT_MIN_EXP      -125
FLT_RADIX        2
FLT_ROUNDS       1
HUGE_VAL         inf
INT_MAX          2147483647
INT_MIN          -2147483648
LDBL_DIG         18
LDBL_EPSILON     undef
LDBL_MANT_DIG    64
LDBL_MAX         undef
LDBL_MAX_10_EXP  4932
LDBL_MAX_EXP     16384
LDBL_MIN         undef
LDBL_MIN_10_EXP  -4931
LDBL_MIN_EXP     -16381
LONG_MAX         9223372036854775807
LONG_MIN         -9223372036854775808
RAND_MAX         2147483647
SCHAR_MAX        127
SCHAR_MIN        -128
SHRT_MAX         32767
SHRT_MIN         -32768
UCHAR_MAX        255
UINT_MAX         4294967295
ULONG_MAX        18446744073709551615
USHRT_MAX        65535

SEE ALSO

This module is part of POSIX-1003 distribution version 0.95.1, built on August 26, 2013. Website: http://perl.overmeer.net. The code is based on POSIX, which is released with Perl itself. See also POSIX::Util for additional functionality.

COPYRIGHTS

Copyrights 2011-2013 on the perl code and the related documentation by [Mark Overmeer]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See http://www.perl.com/perl/misc/Artistic.html