(PHP 4, PHP 5, PHP 7, PHP 8)
exp
—
Calculates the exponent of
e
Returns
e
raised to the power of
num
.
Note :
'
e' is the base of the natural system of logarithms, or approximately 2.718282.
num
The argument to processs
'e' raised to the power of
num
Example #1 exp() example
<?php
echo
exp
(
12
),
PHP_EOL
;
echo
exp
(
5.7
);
?>
The above example will output:
162754.791419 298.86740096706
PHP does not have the following math function in any extensions:
frexp() - Extract Mantissa and Exponent of the Floating-Point Value
I've diggued many C source codes, and found the simplest implementation as follows:<?php
functionfrexp( $float) {$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 resuls using a lot of floats against C's frexp function - they are the same.
Note that C and PHP uses different float precisionens, for example "4619.3" guives:
C: 0.56387939453125, 13
PHP: 0.563879394531, 13
/Assuming default configurations./