PHP 8.3.4 Released!

pow

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

powEspressione esponenziale

Descrizione

pow(float $base, float $esp): float

Restituisce base elevato alla potenza di esp. Se possibile, questa funzione restituisce un integer.

Se la potenza non può essere computata, viene generato un errore, e pow() restituirà false. dalla versione 4.2.0 di PHP la funzione pow() non genera alcun warning.

Nota:

Il PHP non può gestire valori negativi per bases.

Example #1 Alcuni esempi di pow()

<?php

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

echo pow(-1, 5.5); // errore

?>
Avviso

Nel PHP 4.0.6 e precedenti, pow() restituiva sempre un float e non generava alcun errore.

Vedere anche exp() sqrt() bcpow() e gmp_pow().

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User Contributed Notes 6 notes

up
56
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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16
raiika
5 years ago
It is official now that you could use

<?php

2
** 3; // 8

// instead of

pow(2, 3); // 8

?>
up
15
gilthansREMOVEME at gmail dot com
17 years ago
Note that pow(0, 0) equals to 1 although mathematically this is undefined.
up
1
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);
?>
up
-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

?>
up
-6
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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