man3/catan.3

   1 '\" t
   2 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   3 .\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
   4 .\"
   5 .\" SPDX-License-Identifier: GPL-1.0-or-later
   6 .\"
   7 .TH catan 3 (date) "Linux man-pages (unreleased)"
   8 .SH NAME
   9 catan, catanf, catanl \- complex arc tangents
  10 .SH LIBRARY
  11 Math library
  12 .RI ( libm ", " \-lm )
  13 .SH SYNOPSIS
  14 .nf
  15 .B #include <complex.h>
  16 .PP
  17 .BI "double complex catan(double complex " z );
  18 .BI "float complex catanf(float complex " z );
  19 .BI "long double complex catanl(long double complex " z );
  20 .fi
  21 .SH DESCRIPTION
  22 These functions calculate the complex arc tangent of
  23 .IR z .
  24 If \fIy\~=\~catan(z)\fP, then \fIz\~=\~ctan(y)\fP.
  25 The real part of y is chosen in the interval [\-pi/2,pi/2].
  26 .PP
  27 One has:
  28 .PP
  29 .in +4n
  30 .EX
  31 catan(z) = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i)
  32 .EE
  33 .in
  34 .SH ATTRIBUTES
  35 For an explanation of the terms used in this section, see
  36 .BR attributes (7).
  37 .ad l
  38 .nh
  39 .TS
  40 allbox;
  41 lbx lb lb
  42 l l l.
  43 Interface       Attribute       Value
  44 T{
  45 .BR catan (),
  46 .BR catanf (),
  47 .BR catanl ()
  48 T}      Thread safety   MT-Safe
  49 .TE
  50 .hy
  51 .ad
  52 .sp 1
  53 .SH STANDARDS
  54 C11, POSIX.1-2008.
  55 .SH HISTORY
  56 glibc 2.1.
  57 C99, POSIX.1-2001.
  58 .SH EXAMPLES
  59 .\" SRC BEGIN (catan.c)
  60 .EX
  61 /* Link with "\-lm" */
  62 \&
  63 #include <complex.h>
  64 #include <stdio.h>
  65 #include <stdlib.h>
  66 #include <unistd.h>
  67 \&
  68 int
  69 main(int argc, char *argv[])
  70 {
  71     double complex z, c, f;
  72     double complex i = I;
  73 \&
  74     if (argc != 3) {
  75         fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
  76         exit(EXIT_FAILURE);
  77     }
  78 \&
  79     z = atof(argv[1]) + atof(argv[2]) * I;
  80 \&
  81     c = catan(z);
  82     printf("catan() = %6.3f %6.3f*i\en", creal(c), cimag(c));
  83 \&
  84     f = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i);
  85     printf("formula = %6.3f %6.3f*i\en", creal(f), cimag(f));
  86 \&
  87     exit(EXIT_SUCCESS);
  88 }
  89 .EE
  90 .\" SRC END
  91 .SH SEE ALSO
  92 .BR ccos (3),
  93 .BR clog (3),
  94 .BR ctan (3),
  95 .BR complex (7)