Std::cos(std::complex) (3) Linux Manual Page

std::cos(std::complex) – std::cos(std::complex)

Synopsis

Defined in header<complex>

    template <class T>

    complex<T> cos(const complex<T> &z);

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 <iostream>

#include <cmath>

#include <complex>
int main()

{
    std::cout << std::fixed;
    std::complex<double> z(1, 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, 1); // 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)

                   computes sine of a complex number (sin(z))
sin(std::complex) (function template)
                   computes tangent of a complex number (tan(z))
tan(std::complex) (function template)
acos(std::complex) computes arc cosine of a complex number (arccos(z))
                   (function template)
(C++11)
cos
cosf
cosl computes cosine (cos(x))
                   (function)
(C++11)
(C++11)
                   applies the function std::cos to each element of valarray
cos(std::valarray) (function template)

std::cos(std::complex) (3) Linux Manual Page