##### Synopsis

    #include <math.h>
    float expf(float x);

##### Description

expf computes the base-e exponential of x.

##### Fast math library behavior

If |x| >~ 88.722, errno is set to EDOM and expf returns HUGE_VALF.

##### IEC 60559 math library behavior

If x is NaN, expf returns NaN.
If x is ∞, expf returns ∞
If x is -∞, expf returns 0.

##### Portability

expf conforms to ISO/IEC 9899:1990 (C90) and ISO/IEC 9899:1999 (C99).