(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)
expm1 — Returns exp(number) - 1, computed in a way that is accurate even when the value of number is close to zero
$num): float
expm1() returns the equivalent to
'exp(num) - 1' computed in a way that is
accurate even if the value of num is near zero,
a case where 'exp (num) - 1' would be
inaccurate due to subtraction of two numbers that are nearly equal.
numThe argument to process
'e' to the power of num minus one