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

exp — Calculates the exponent of e

Description

Note:

'e' is the base of the natural system of logarithms, or approximately 2.718282.

Parameters

num

The argument to process

Return Values

'e' raised to the power of num

Examples

<?php
echo exp(12), PHP_EOL;
echo exp(5.7);
?>

162754.791419
298.86740096706

See Also

• log() - Natural logarithm
• pow() - Exponential expression

3

PHP does not have the following math function in any extensions:
frexp() - Extract Mantissa and Exponent of the Floating-Point Value
I've digged many C source codes, and found the simplest implementation as follows:
<?php
function frexp ( $float ) {
  $exponent = ( floor(log($float, 2)) + 1 );
  $mantissa = ( $float * pow(2, -$exponent) );
  return(
    array($mantissa, $exponent)
  );
}
print_r(frexp(0.0345));
print_r(frexp(21.539));
?>

Array
(
    [0] => 0.552
    [1] => -4
)
Array
(
    [0] => 0.67309375
    [1] => 5
)
I have compared the results using a lot of floats against C's frexp function - they are the same.
Note that C and PHP uses different float precisions, for example "4619.3" gives:
C: 0.56387939453125, 13
PHP: 0.563879394531, 13
/Assuming default configurations./