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.
pow
(PHP 4, PHP 5, PHP 7, PHP 8)
pow — Espressione 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.
add a note
User Contributed Notes 6 notes
chris at ocportal dot com ¶
10 years ago
Roman ¶
1 year ago
If you use negative numbers, you need to use brackets for using with **
<?php
-1 ** 2; // -1
(-1) ** 2; // 1
?>
raiika ¶
4 years ago
It is official now that you could use
<?php
2 ** 3; // 8
// instead of
pow(2, 3); // 8
?>
gilthansREMOVEME at gmail dot com ¶
15 years ago
Note that pow(0, 0) equals to 1 although mathematically this is undefined.
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);
?>
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
