PHP log10() Function

Definition and Usage

The log10 () function calculates base-10 logarithm of a number.

Base-10 logarithm is also called common or sandard algorithm. The log10(x) function calculates log₁₀x. It is related to natural algorithm by following equation −

log₁₀x=log_ex/log_e10 So that

log₁₀100=log_e100/log_e10 = 2

In PHP, log₁₀ is represented by log10() function

Syntax

log10 ( float $arg ) : float

Parameters

Return Values

PHP log10() function returns base-10 logarithm of arg.

PHP Version

This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x.

Example

Following example calculates base-10 logarithm of 100

<?php
   $arg=100;
   echo "log10(" . $arg. ")=" . log10($arg) . "\n";
?>

Output

This will produce following result −

log10(100)=2

Example

Following code calculates base-10 logarithm of Euler Number M_E. The result is equal to a predefined constant M_LOG10E−

<?php
   $arg=M_E;
   echo "log10(" . $arg. ")=" . log10($arg) . "\n";
   echo "predefined constant M_LOG10E=" . M_LOG10E;
?>

Output

This will produce following result −

log10(2.718281828459)=0.43429448190325
predefined constant M_LOG10E=0.43429448190325

Example

Following example calculates log₁₀0 and returns -infinity. −

<?php
   $arg=0;
   echo "log10(" . $arg. ")=" . log10($arg) . "\n";
?>

Output

This will produce following result −

log10(0)=-INF

Example

Similarly sqrt(-1) results in NAN. Hence its log10() also returns NAN −

<?php
   $arg=sqrt(-1);
   echo "log10(" . $arg. ")=" . log10($arg) . "\n";
?>

Output

This will produce following result −

log10(NAN)=NAN