The "exp()" function calculates the exponent of e.

    exp(x)

In the above syntax "x" is the number whose exponent(e) is to be calculated.

    <?php
    echo exp(1) . "\n";
    echo exp(5.7);
    ?>

    2.718281828459045
    298.87

In the above example the exponent(e) value of numbers "1", "5.7" is calculated.