std::acos

 

C++

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Functions
Basic operations
abs(int) labs llabs imaxabs (C++11) abs(float) fabs div ldiv lldiv imaxdiv (C++11) fmod	remainder (C++11) remquo (C++11) fma (C++11) fmax (C++11) fmin (C++11) fdim (C++11) nan nanf nanl (C++11) (C++11) (C++11)
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erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
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ldexp scalbn scalbln (C++11) (C++11) ilogb (C++11) logb (C++11)	frexp modf nextafter nexttoward (C++11) (C++11) copysign (C++11)
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fpclassify (C++11) isfinite (C++11) isinf (C++11) isnan (C++11) isnormal (C++11) signbit (C++11)	isgreater (C++11) isgreaterequal (C++11) isless (C++11) islessequal (C++11) islessgreater (C++11) isunordered (C++11)
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HUGE_VALF HUGE_VAL HUGE_VALL (C++11) (C++11) INFINITY (C++11) NAN (C++11) math_errhandling MATH_ERRNO MATH_ERREXCEPT (C++11)	FP_NORMAL FP_SUBNORMAL FP_ZERO FP_INFINITE FP_NAN (C++11) (C++11) (C++11) (C++11) (C++11)

 

Defined in header <cmath>
float       acos( float arg );
double      acos( double arg );
long double acos( long double arg );
double      acos( Integral arg );		(since C++11)

Computes arc cosine of arg

Parameters

arg

-

floating point value

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.

Example

run this code

#include <cmath>
#include <iostream>
 
int main()
{
    std::cout << "The number pi is " << std::acos(-1) << '\n';
}

Output:

The number pi is 3.14159

See also

asin	computes arc sine (arcsin(x)) (function)
atan	computes arc tangent (arctan(x)) (function)
atan2	arc tangent, using signs to determine quadrants (function)
cos	computes cosine (cos(x)) (function)
acos(std::complex) (C++11)	computes arc cosine of a complex number (arccos(z)) (function template)
acos(std::valarray)	applies the function std::acos to each element of valarray (function template)