Calculates the inverse sine of a number
#include <math.h> double asin ( double x ); float asinf ( float x ); (C99) long double asinl ( long double x ); (C99)
asin( ) implements the inverse sine function, commonly called arc sine. The argument x must be between -1 and 1, inclusive: -1 x 1. If x is outside the function's domainthat is, if x is greater than 1 or less than -1the function incurs a domain error.
The return value is given in radians, and is thus in the range -p/2 asin(x) p/2.
/* * Calculate the altitude of the sun (its angle upward from the horizon) * given the height of a vertical object and the length of the object's * shadow. */ #define PI 3.141593 #define DEG_PER_RAD (180.0/PI) float height = 2.20F; float length = 1.23F; float altitude = asinf( height / sqrtf( height*height + length*length )); printf( "The sun's altitude is %2.0f\xB0.\n", altitude * DEG_PER_RAD );
This code produces the following output:
The sun's altitude is 61°.
Arcsine functions for complex numbers: casin( ), casinf( ), and casinl( )