std::atan2

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Numerics library

Common mathematical functions

Floating-point environment

Complex numbers

Numeric arrays

Pseudo-random number generation

Compile-time rational arithmetic (C++11)

Generic numeric operations

iota (C++11)

accumulate

inner_product

adjacent_difference

partial_sum

 

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)
Exponential functions
exp exp2 (C++11) expm1 (C++11)	log log10 log1p (C++11) log2 (C++11)
Power functions
sqrt cbrt (C++11)	hypot (C++11) pow
Trigonometric and hyperbolic functions
sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)

Error and gamma functions
erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
Nearest integer floating point operations
ceil floor roundlroundllround (C++11)(C++11)(C++11)	trunc (C++11) nearbyint (C++11) rintlrintllrint (C++11)(C++11)(C++11)
Floating point manipulation functions
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       atan2( float y, float x );	(1)
double      atan2( double y, double x );	(2)
long double atan2( long double y, long double x );	(3)
Promoted    atan2( Arithmetic1 y, Arithmetic2 x );	(4)	(since C++11)

Computes the inverse tangent of y/x using the signs of arguments to correctly determine quadrant.

4) If any argument has integral type, it is cast to double. If any other argument is long double, then the return type is long double, otherwise it is double.

Parameters

x, y

-

values of floating-point or integral types

Return value

Arc tangent of y/x in radians in the range of [-π; π] radians.

Y argument

Return value

X argument

Example

Run this code

#include <cmath>
#include <utility>
#include <iostream>
 
std::pair<double, double> cartesian_to_polar(double x, double y)
{
    return {std::hypot(x, y), std::atan2(y,x)};
}
 
int main()
{
    std::pair<double, double> polar = cartesian_to_polar(1, 1);
    std::cout << "(1,1) cartesian is (" << polar.first
               << "," << polar.second<< ") polar\n";
}

Output:

(1,1) cartesian is (1.41421,0.785398) polar

See also

atan	computes arc tangent (arctan(x)) (function)
asin	computes arc sine (arcsin(x)) (function)
acos	computes arc cosine (arccos(x)) (function)
tan	computes tangent (tan(x)) (function)
C documentation for atan2