expm1() [5/6]

var stan::math::expm1 ( const var &  a )

inline

The exponentiation of the specified variable minus 1 (C99).

The derivative is given by

$\frac{d}{dx} \exp(a) - 1 = \exp(a)$.

$$\mbox{expm1}(x) = \begin{cases} e^x-1 & \mbox{if } -\infty\leq x \leq \infty \\[6pt] \textrm{NaN} & \mbox{if } x = \textrm{NaN} \end{cases}$$

$$\frac{\partial\, \mbox{expm1}(x)}{\partial x} = \begin{cases} e^x & \mbox{if } -\infty\leq x\leq \infty \\[6pt] \textrm{NaN} & \mbox{if } x = \textrm{NaN} \end{cases}$$

Parameters

a	The variable.

Returns

Two to the power of the specified variable.

Definition at line 38 of file expm1.hpp.