pow

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

powExponential expression

Description

pow(mixed $num, mixed $exponent): int|float|object

Returns num raised to the power of exponent.

Note:

It is possible to use the ** operator instead.

Parameters

num

The base to use

exponent

The exponent

Return Values

num raised to the power of exponent. If both arguments are non-negative integers and the result can be represented as an integer, the result will be returned with int type, otherwise it will be returned as a float.

Examples

Example #1 Some examples of pow()

<?php

var_dump
(pow(2, 8)); // int(256)
echo pow(-1, 20); // 1
echo pow(0, 0); // 1
echo pow(10, -1); // 0.1

echo pow(-1, 5.5); // NAN
?>

Notes

Note:

This function will convert all input to a number, even non-scalar values, which could lead to weird results.

See Also

  • exp() - Calculates the exponent of e
  • sqrt() - Square root
  • bcpow() - Raise an arbitrary precision number to another
  • gmp_pow() - Raise number into power

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User Contributed Notes 6 notes

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42
chris at ocportal dot com
11 years ago
Many notations use "^" as a power operator, but in PHP (and other C-based languages) that is actually the XOR operator. You need to use this 'pow' function, there is no power operator.

i.e. 3^2 means "3 XOR 2" not "3 squared".

It is particular confusing as when doing Pythagoras theorem in a 'closet points' algorithm using "^" you get results that look vaguely correct but with an error.
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1
Roman
3 years ago
If you use negative numbers, you need to use brackets for using with **

<?php

-1 ** 2; // -1

(-1) ** 2; // 1

?>
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8
raiika
5 years ago
It is official now that you could use

<?php

2
** 3; // 8

// instead of

pow(2, 3); // 8

?>
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13
gilthansREMOVEME at gmail dot com
17 years ago
Note that pow(0, 0) equals to 1 although mathematically this is undefined.
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3
scott at arciszewski dot me
10 years ago
As of PHP 5.6.0alpha2, there is now an exponentiation operator. If this is kept in the final release, it may be worth noting here.

<?php
// These two will be equivalent as of PHP 5.6.0
$x = $y ** 2;
$x = pow($y, 2);
?>
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0
jaxx1rr at gmail dot com
4 years ago
funny thing

number_format(pow(2, 1023));
gives a long number

but number_format(pow(2, 1024));
gives inf
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