newlib/libm/complex/carg.c

   1 /* $NetBSD: carg.c,v 1.1 2007/08/20 16:01:31 drochner Exp $ */
   2
   3 /*
   4  * Written by Matthias Drochner <drochner@NetBSD.org>.
   5  * Public domain.
   6  *
   7  * imported and modified include for newlib 2010/10/03
   8  * Marco Atzeri <marco_atzeri@yahoo.it>
   9  */
  10
  11 /*
  12 FUNCTION
  13         <<carg>>, <<cargf>>---argument (phase angle)
  14
  15 INDEX
  16         carg
  17 INDEX
  18         cargf
  19
  20 SYNOPSIS
  21        #include <complex.h>
  22        double carg(double complex <[z]>);
  23        float cargf(float complex <[z]>);
  24
  25
  26 DESCRIPTION
  27         These functions compute the argument (also called phase angle)
  28         of <[z]>, with a branch cut along the negative real axis.
  29
  30         <<cargf>> is identical to <<carg>>, except that it performs
  31         its calculations on <<floats complex>>.
  32
  33 RETURNS
  34         @ifnottex
  35         The carg functions return the value of the argument in the
  36         interval [-pi, +pi]
  37         @end ifnottex
  38         @tex
  39         The carg functions return the value of the argument in the
  40         interval [$-\pi$, $+\pi$]
  41         @end tex
  42
  43 PORTABILITY
  44         <<carg>> and <<cargf>> are ISO C99
  45
  46 QUICKREF
  47         <<carg>> and <<cargf>> are ISO C99
  48
  49 */
  50
  51 #include <complex.h>
  52 #include <math.h>
  53
  54 double
  55 carg(double complex z)
  56 {
  57
  58         return atan2( cimag(z) , creal(z) );
  59 }