std::cosh(std::complex)(3)

NAME
std::cosh(std::complex) - std::cosh(std::complex)

Synopsis
   Defined in header <complex>
   template< class T > (since C++11)
   complex<T> cosh( const complex<T>& z );
   Computes complex hyperbolic cosine of a complex value z.

Parameters
   z - complex value

Return value
   If no errors occur, complex hyperbolic cosine of z is returned
  Error handling and special values
   Errors are reported consistent with math_errhandling
   If the implementation supports IEEE floating-point arithmetic,
     * std::cosh(std::conj(z)) == std::conj(std::cosh(z))
     * std::cosh(z) == std::cosh(-z)
     * If z is (+0,+0), the result is (1,+0)
     * If z is (+0,+∞), the result is (NaN,±0) (the sign of the imaginary part is
       unspecified) and FE_INVALID is raised
     * If z is (+0,NaN), the result is (NaN,±0) (the sign of the imaginary part is
       unspecified)
     * If z is (x,+∞) (for any finite non-zero x), the result is (NaN,NaN) and
       FE_INVALID is raised
     * If z is (x,NaN) (for any finite non-zero x), the result is (NaN,NaN) and
       FE_INVALID may be raised
     * If z is (+∞,+0), the result is (+∞,+0)
     * If z is (+∞,y) (for any finite non-zero y), the result is +∞cis(y)
     * If z is (+∞,+∞), the result is (±∞,NaN) (the sign of the real part is
       unspecified) and FE_INVALID is raised
     * If z is (+∞,NaN), the result is (+∞,NaN)
     * If z is (NaN,+0), the result is (NaN,±0) (the sign of the imaginary part is
       unspecified)
     * If z is (NaN,+y) (for any finite non-zero y), the result is (NaN,NaN) and
       FE_INVALID may be raised
     * If z is (NaN,NaN), the result is (NaN,NaN)
   where cis(y) is cos(y) + i sin(y)

Notes
   Mathematical definition of hyperbolic cosine is cosh z =
   ez
   +e-z
   2
   Hyperbolic cosine is an entire function in the complex plane and has no branch cuts.
   It is periodic with respect to the imaginary component, with period 2πi

Examples
// Run this code
 #include <iostream>
 #include <cmath>
 #include <complex>
 int main()
 {
     std::cout << std::fixed;
     std::complex<double> z(1, 0); // behaves like real cosh along the real line
     std::cout << "cosh" << z << " = " << std::cosh(z)
               << " (cosh(1) = " << std::cosh(1) << ")\n";
     std::complex<double> z2(0, 1); // behaves like real cosine along the imaginary line
     std::cout << "cosh" << z2 << " = " << std::cosh(z2)
               << " ( cos(1) = " << std::cos(1) << ")\n";
 }

Output:
 cosh(1.000000,0.000000) = (1.543081,0.000000) (cosh(1) = 1.543081)
 cosh(0.000000,1.000000) = (0.540302,0.000000) ( cos(1) = 0.540302)

See also
                       computes hyperbolic sine of a complex number (\({\small\sinh{z}
   sinh(std::complex) }\)sinh(z))
                       (function template)
                       computes hyperbolic tangent of a complex number
   tanh(std::complex) (\({\small\tanh{z} }\)tanh(z))
                       (function template)
   acosh(std::complex) computes area hyperbolic cosine of a complex number
   (C++11) (\({\small\operatorname{arcosh}{z} }\)arcosh(z))
                       (function template)
   cosh
   coshf computes hyperbolic cosine (\({\small\cosh{x} }\)cosh(x))
   coshl (function)
   (C++11)
   (C++11)
   cosh(std::valarray) applies the function std::cosh to each element of valarray
                       (function template)