RETURN VALUES
 The  asin and the  asinf functions return the arc sine in the range 
.Bk -words [-pi/2, +pi/2] 
.Ek  radians. If: 
| x | > 1
  asin x raises an invalid exception and returns an NaN.   
SEE ALSO
 acos(3), atan(3), atan2(3), cos(3), cosh(3), fenv(3), math(3), sin(3), sinh(3), tan(3), tanh(3)  
STANDARDS