##### Synopsis

    #include <math.h>
    float asinf(float val);

##### Description

asinf returns the principal value, in radians, of the inverse circular sine of val. The principal value lies in the interval [-PI/2, +PI/2] radians.

##### Fast math library behavior

If |x| > 1, errno is set to EDOM and asinf returns HUGE_VALF.

##### IEC 60559 math library behavior

If x is NaN, asinf returns x.
If |x| > 1, asinf returns NaN with invalid signal.

##### Portability

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