acos, acosf, acosl - Arc cosine

Definition	#include <math.h> double acos(double x); float acosf(float x); (C11) long double acosl(long double x); (C11) These functions are the inverse function of the corresponding  cos-functions. hey return the principal value (i.e. corresponding angle in radians) of the arc cosine of a floating-point number x  in the range [-1.0, +1.0].
Return val.	arc cosine(x)
		a floating-point number of type double from [0, pi] for values x in the interval [-1.0, +1.0].
	0	for values outside the interval [-1.0, +1.0]. In addition, errno is set to EDOM (domain error, i.e. argument too large).
Example	The following program prints the corresponding arc cosine values for input values in the interval [0.0, 1.0]: #include <math.h> #include <stdio.h> int main(void) { double x; for(x = 0.0; x < 1.0; x = x + 0.1) printf("x = %g : acos(%g) = %g\n", x, x, acos(x)); return 0; }
See also	cos, sin, tan, asin, atan, atan2