man3/carg.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" SPDX-License-Identifier: GPL-1.0-or-later
   4 .\"
   5 .TH carg 3 (date) "Linux man-pages (unreleased)"
   6 .SH NAME
   7 carg, cargf, cargl \- calculate the complex argument
   8 .SH LIBRARY
   9 Math library
  10 .RI ( libm ", " \-lm )
  11 .SH SYNOPSIS
  12 .nf
  13 .B #include <complex.h>
  14 .PP
  15 .BI "double carg(double complex " z ");"
  16 .BI "float cargf(float complex " z ");"
  17 .BI "long double cargl(long double complex " z ");"
  18 .fi
  19 .SH DESCRIPTION
  20 These functions calculate the complex argument (also called phase angle) of
  21 .IR z ,
  22 with a branch cut along the negative real axis.
  23 .PP
  24 A complex number can be described by two real coordinates.
  25 One may use rectangular coordinates and gets
  26 .PP
  27 .in +4n
  28 .EX
  29 z = x + I * y
  30 .EE
  31 .in
  32 .PP
  33 where
  34 .I x\~=\~creal(z)
  35 and
  36 .IR y\~=\~cimag(z) .
  37 .PP
  38 Or one may use polar coordinates and gets
  39 .PP
  40 .in +4n
  41 .EX
  42 z = r * cexp(I * a)
  43 .EE
  44 .in
  45 .PP
  46 where
  47 .I r\~=\~cabs(z)
  48 is the "radius", the "modulus", the absolute value of
  49 .IR z ,
  50 and
  51 .I a\~=\~carg(z)
  52 is the "phase angle", the argument of
  53 .IR z .
  54 .PP
  55 One has:
  56 .PP
  57 .in +4n
  58 .EX
  59 tan(carg(z)) = cimag(z) / creal(z)
  60 .EE
  61 .in
  62 .SH RETURN VALUE
  63 The return value is in the range of [\-pi,pi].
  64 .SH VERSIONS
  65 These functions first appeared in glibc in version 2.1.
  66 .SH ATTRIBUTES
  67 For an explanation of the terms used in this section, see
  68 .BR attributes (7).
  69 .ad l
  70 .nh
  71 .TS
  72 allbox;
  73 lbx lb lb
  74 l l l.
  75 Interface       Attribute       Value
  76 T{
  77 .BR carg (),
  78 .BR cargf (),
  79 .BR cargl ()
  80 T}      Thread safety   MT-Safe
  81 .TE
  82 .hy
  83 .ad
  84 .sp 1
  85 .SH STANDARDS
  86 C99, POSIX.1-2001, POSIX.1-2008.
  87 .SH SEE ALSO
  88 .BR cabs (3),
  89 .BR complex (7)