| 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
#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)
See also
| computes sine of a complex number (sin(z)) (function template) | |
| computes tangent of a complex number (tan(z)) (function template) | |
| (C++11) | computes arc cosine of a complex number (arccos(z)) (function template) |
| computes cosine (cos(x)) (function) | |
applies the function std::cos to each element of valarray (function template) | |
C documentation for ccos | |
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