man3/carg.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\"
   3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
   4 .\" Distributed under GPL
   5 .\" %%%LICENSE_END
   6 .\"
   7 .TH CARG 3 2008-08-11 "" "Linux Programmer's Manual"
   8 .SH NAME
   9 carg, cargf, cargl \- calculate the complex argument
  10 .SH SYNOPSIS
  11 .B #include <complex.h>
  12 .sp
  13 .BI "double carg(double complex " z ");"
  14 .br
  15 .BI "float cargf(float complex " z ");"
  16 .br
  17 .BI "long double cargl(long double complex " z ");"
  18 .sp
  19 Link with \fI\-lm\fP.
  20 .SH DESCRIPTION
  21 A complex number can be described by two real coordinates.
  22 One may use rectangular coordinates and gets
  23
  24 .nf
  25     z = x + I * y
  26 .fi
  27
  28 where
  29 .IR "x\ =\ creal(z)"
  30 and
  31 .IR "y\ =\ cimag(z)" .
  32 .LP
  33 Or one may use polar coordinates and gets
  34 .nf
  35
  36     z = r * cexp(I * a)
  37
  38 .fi
  39 where
  40 .IR "r\ =\ cabs(z)"
  41 is the "radius", the "modulus", the absolute value of
  42 .IR z ,
  43 and
  44 .IR "a\ =\ carg(z)"
  45 is the "phase angle", the argument of
  46 .IR z .
  47 .LP
  48 One has:
  49 .nf
  50
  51     tan(carg(z)) = cimag(z) / creal(z)
  52 .fi
  53 .SH RETURN VALUE
  54 The return value is the range of [\-pi,pi].
  55 .SH VERSIONS
  56 These functions first appeared in glibc in version 2.1.
  57 .SH ATTRIBUTES
  58 For an explanation of the terms used in this section, see
  59 .BR attributes (7).
  60 .TS
  61 allbox;
  62 lbw24 lb lb
  63 l l l.
  64 Interface       Attribute       Value
  65 T{
  66 .BR carg (),
  67 .BR cargf (),
  68 .BR cargl ()
  69 T}      Thread safety   MT-Safe
  70 .TE
  71 .SH CONFORMING TO
  72 C99.
  73 .SH SEE ALSO
  74 .BR cabs (3),
  75 .BR complex (7)