bcdiv

(PHP 4, PHP 5, PHP 7, PHP 8)

bcdiv — Divide two arbitrary precision numbers

Description

bcdiv(string $num1, string $num2, ?int $scale = null): string

Divides num1 by num2.

Parameters

num1: The dividend, as a string.
num2: The divisor, as a string.
scale: This parameter is used to set the number of digits after the decimal place in the result. If null, it will default to the default scale set with bcscale(), or fallback to the value of the bcmath.scale INI directive.

Return Values

Returns the result of the division as a string.

Errors/Exceptions

This function throws a ValueError in the following cases:

num1 or num2 is not a well-formed BCMath numeric string.
scale is outside the valid range.

This function throws a DivisionByZeroError exception if num2 is 0.

Changelog

Version	Description
8.0.0	`scale` is now nullable.
8.0.0	Dividing by `0` now throws a DivisionByZeroError exception instead of returning `null`.

Examples

Example #1 bcdiv() example

<?php

echo bcdiv('105', '6.55957', 3);  // 16.007

?>

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User Contributed Notes 1 note

down

MM ¶

16 years ago

Perhaps some one can find useful this function to compute the modular inverse of a integer (extended euclidean algorithm):

  function invmod($a,$b) {
    $n=$b;
    $x=0; $lx=1; $y=1; $ly=0;
    while ($b) {
      $t=$b;
      $q=bcdiv($a,$b,0);
      $b=bcmod($a,$b);
      $a=$t;
      $t=$x; $x=bcsub($lx,bcmod(bcmul($q,$x),$n)); $lx=$t;
      $t=$y; $y=bcsub($ly,bcmod(bcmul($q,$y),$n)); $ly=$t;
    }
    if (bccomp($lx,0) == -1)
      $lx=bcadd($lx,$n);
    return $lx;
  }

  // verify

  $n="2447995268898324993537772139997802321";
  $t="64941057316178801556773346239351236811";
  $m="123456789";
  $i=invmod($t,$n);
  // (t*m)*inv(t) is m
  echo bcmod(bcmul(bcmod(bcmul($t,$m),$n),$i),$n) == $m;