##### Synopsis

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

##### Description

tanf returns the radian circular tangent of x.

##### Fast math library special cases

If |x| > 10^9, errno is set to EDOM and tanf returns HUGE_VALF.

##### IEC 60559 math library special cases

If x is NaN, tanf returns x.
If |x| is ?, tanf returns NaN with invalid signal.

##### Portability

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