## Properties of complex numbers

Function: double gsl_complex_arg (gsl_complex z)
This function returns the argument of the complex number z, @math{\arg(z)}, where @c{$-\pi < \arg(z) \leq \pi$} @math{-\pi < \arg(z) <= \pi}.

Function: double gsl_complex_abs (gsl_complex z)
This function returns the magnitude of the complex number z, @math{|z|}.

Function: double gsl_complex_abs2 (gsl_complex z)
This function returns the squared magnitude of the complex number z, @math{|z|^2}.

Function: double gsl_complex_logabs (gsl_complex z)
This function returns the natural logarithm of the magnitude of the complex number z, @math{\log|z|}. It allows an accurate evaluation of @math{\log|z|} when @math{|z|} is close to one. The direct evaluation of log(gsl_complex_abs(z)) would lead to a loss of precision in this case.