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(-120); // 1
echo pow(00); // 1

echo pow(-15.5); // 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

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42
chris at ocportal dot com
10 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
1 year 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
4 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
15 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
8 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
3 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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