7.2.42 Math::BigFloat - Arbitrary-Length, Floating-Point Math Package

use Math::BigFloat;

$f = Math::BigFloat->new($string);

# 

NSTR

 is a number string; 

SCALE

 is an integer value.
# In all following cases $f remains unchanged.
# All methods except fcmp() return a number string.
$f->fadd(

NSTR

);          # return sum of 

NSTR

 and $f
$f->fsub(

NSTR

);          # return $f minus 

NSTR


$f->fmul(

NSTR

);          # return $f multiplied by 

NSTR


$f->fdiv(

NSTR

[,

SCALE

]);  # return $f divided by 

NSTR

 to 

SCALE

 places
$f->fneg();              # return negative of $f
$f->fabs();              # return absolute value of $f
$f->fcmp(

NSTR

);          # compare $f to 

NSTR

; see below for return value
$f->fround(

SCALE

);       # return rounded value of $f to 

SCALE

 digits
$f->ffround(

SCALE

);      # return rounded value of $f at 

SCALEth

 place
$f->fnorm();             # return normalization of $f
$f->fsqrt([

SCALE

]);      # return sqrt of $f to 

SCALE

 places

This module allows you to use floating-point numbers of arbitrary length. For example:

$float = new Math::BigFloat "2.123123123123123123123123123123123";

Number strings ( NSTR s) have the form, /[+-]\d*\.?\d*E[+-]\d+/ . Embedded white space is ignored, so that the number strings used in the following two lines are identical:

$f = Math::BigFloat->new("-20.0    0732");
$g = $f->fmul("-20.00732");

The return value NaN indicates either that an input parameter was "Not a Number", or else that you tried to divide by zero or take the square root of a negative number. The fcmp() method returns -1 , 0 , or 1 depending on whether $f is less than, equal to, or greater than the number string given as an argument. If the number string is undefined or null, the undefined value is returned.

If SCALE is unspecified, division is computed to the number of digits given by:

max($div_scale, length(dividend)+length(divisor))

A similar default scale value is computed for square roots.

When you use this module, Perl's basic math operations are overloaded with routines from Math::BigFloat. Therefore, you don't have to employ the methods shown above to multiply, divide, and so on. You can rely instead on the usual operators. Given this code:

$f = Math::BigFloat->new("20.00732");
$g = Math::BigFloat->new("1.7");

the following six lines all yield the corresponding values for $h :

$h = 20.00732 * 1.7;    # 34.012444 (ordinary math--$h is not an object)
$h = $f * $g;           # "34.012444" ($h is now a BigFloat object)
$h = $f * 1.7;          # "34.012444" ($h is now a BigFloat object)
$h = 20.00732 * $g;     # "34.012444" ($h is now a BigFloat object)
$h = $f->fmul($g);      # "+34012444E-6" ($h is now a BigFloat object)
$h = $f->fmul(1.7);     # "+34012444E-6" ($h is now a BigFloat object)