acos

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Defined in header <math.h>
float       acosf( float arg );
(since C99)
double      acos( double arg );
long double acosl( long double arg );
(since C99)

Computes arc cosine of arg

[edit] Parameters

arg - floating point value

[edit] Return value

Arc cosine of arg in radians in the range of [0; π] radians.

Domain error occurs if arg is outside the range [-1.0; 1.0]. NAN is returned in that case.

[edit] See also

computes arc sine (arcsin(x))
(function)
computes arc tangent (arctan(x))
(function)
arc tangent, using signs to determine quadrants
(function)
computes cosine (cos(x))
(function)