std::cos(std::complex)

 

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std::complex

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complex::complex complex::operator= complex::real complex::imag	complex::operator+=complex::operator-=complex::operator*=complex::operator/=
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operator+operator- operator+operator-operator*operator/ operator==operator!= (until C++20)   operator<<operator>> get(std::complex) (C++26)	real imag abs arg norm conj proj (C++11) polar operator""ioperator""ifoperator""il (C++14)(C++14)(C++14)
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sin   cos tan asin (C++11) acos (C++11) atan (C++11)
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sinh   cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)
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Defined in header <complex>
template< class T > complex<T> cos( const complex<T>& z );

See More

Computes complex cosine of a complex value z.

Parameters

z

-

complex value

Return value

If no errors occur, the complex cosine of z is returned.

Errors and special cases are handled as if the operation is implemented by std::cosh(i * z), where i is the imaginary unit.

Notes

The cosine is an entire function on the complex plane, and has no branch cuts.

Mathematical definition of the cosine is

cos z =

eiz +e-iz

2

.

Example

Run this code

#include <cmath>
#include <complex>
#include <iostream>

int main()
{
    std::cout << std::fixed;
    std::complex<double> z(1.0, 0.0); // behaves like real cosine along the real line
    std::cout << "cos" << z << " = " << std::cos(z)
              << " ( cos(1) = " << std::cos(1) << ")\n";

    std::complex<double> z2(0.0, 1.0); // behaves like real cosh along the imaginary line
    std::cout << "cos" << z2 << " = " << std::cos(z2)
              << " (cosh(1) = " << std::cosh(1) << ")\n";
}

Output:

cos(1.000000,0.000000) = (0.540302,-0.000000) ( cos(1) = 0.540302)
cos(0.000000,1.000000) = (1.543081,-0.000000) (cosh(1) = 1.543081)

See also

sin(std::complex)	computes sine of a complex number (\({\small\sin{z}}\)sin(z)) (function template)
tan(std::complex)	computes tangent of a complex number (\({\small\tan{z}}\)tan(z)) (function template)
acos(std::complex) (C++11)	computes arc cosine of a complex number (\({\small\arccos{z}}\)arccos(z)) (function template)
coscosfcosl (C++11)(C++11)	computes cosine (\({\small\cos{x}}\)cos(x)) (function)
cos(std::valarray)	applies the function std::cos to each element of valarray (function template)
C documentation for ccos