std::acos

 

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Common mathematical functions

Functions
Basic operations
abs(int)labsllabsimaxabs (C++11) abs(float)fabs divldivlldivimaxdiv (C++11) fmod	remainder (C++11) remquo (C++11) fma (C++11) fmax (C++11) fmin (C++11) fdim (C++11) nannanfnanl (C++11)(C++11)(C++11)
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sqrt cbrt (C++11)	hypot (C++11) pow
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sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)

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erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
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ceil floor roundlroundllround (C++11)(C++11)(C++11)	trunc (C++11) nearbyint (C++11) rintlrintllrint (C++11)(C++11)(C++11)
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ldexp scalbnscalbln (C++11)(C++11) ilogb (C++11) logb (C++11)	frexp modf nextafternexttoward (C++11)(C++11) copysign (C++11)
Classification/Comparison
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)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11) INFINITY (C++11) NAN (C++11) math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_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

-

value of a floating-point or Integral type

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)
C documentation for acos