1.5 asin, asinf—arc sine

Synopsis

#include <math.h>
double asin(double x);
float asinf(float x);

Description

asin computes the inverse sine (arc sine) of the argument x. Arguments to asin must be in the range -1 to 1.

asinf is identical to asin, other than taking and returning floats.

Returns
asin returns values in radians, in the range of -pi/2 to pi/2.

If x is not in the range -1 to 1, asin and asinf return NaN (not a number), and the global variable errno is set to EDOM.