std::cos(std::complex)
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std::complex
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(C++26)
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(C++26)
Defined in header
<complex>
template< class T >
complex<T> cos( const complex<T>& z );
complex<T> cos( const complex<T>& z );
Computes complex cosine of a complex value z.
Contents
[edit] Parameters
z
-
complex value
[edit] 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.
[edit] 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
+e-iz
2
.
[edit] 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)
[edit] See also
(C++11)
(function template) [edit]
C documentation for ccos