### 5.5 Complex Trigonometric Functions

Function: gsl_complex gsl_complex_sin (gsl_complex z)

  This function returns the complex sine of the complex number z, \sin(z) = (\exp(iz) - \exp(-iz))/(2i).

Function: gsl_complex gsl_complex_cos (gsl_complex z)

  This function returns the complex cosine of the complex number z, \cos(z) = (\exp(iz) + \exp(-iz))/2.

Function: gsl_complex gsl_complex_tan (gsl_complex z)

  This function returns the complex tangent of the complex number z, \tan(z) = \sin(z)/\cos(z).

Function: gsl_complex gsl_complex_sec (gsl_complex z)

  This function returns the complex secant of the complex number z, \sec(z) = 1/\cos(z).

Function: gsl_complex gsl_complex_csc (gsl_complex z)

  This function returns the complex cosecant of the complex number z, \csc(z) = 1/\sin(z).

Function: gsl_complex gsl_complex_cot (gsl_complex z)

  This function returns the complex cotangent of the complex number z, \cot(z) = 1/\tan(z).