The Exponential Function Minus One: expm1

Syntax
y = expm1(x)

Description
Returns the value of the exponential function minus one which is defined by y == exp(x) - 1 .

x, y
See the possible types for a unary standard math function.

If this preprocessor symbol is true (1), and x is an AD type, this is an atomic operation .
If this preprocessor symbol is false (0), CppAD uses the representation $$\R{expm1} (x) = \exp(x) - 1$$ to compute this function.