man3/catan.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\" and Copyright (C) 2011 Michael Kerrisk <mtk.manpages@gmail.com>
   3 .\"
   4 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
   5 .\" Distributed under GPL
   6 .\" %%%LICENSE_END
   7 .\"
   8 .TH CATAN 3 2019-03-06 "" "Linux Programmer's Manual"
   9 .SH NAME
  10 catan, catanf, catanl \- complex arc tangents
  11 .SH SYNOPSIS
  12 .B #include <complex.h>
  13 .PP
  14 .BI "double complex catan(double complex " z );
  15 .br
  16 .BI "float complex catanf(float complex " z );
  17 .br
  18 .BI "long double complex catanl(long double complex " z );
  19 .PP
  20 Link with \fI\-lm\fP.
  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 .nf
  30     catan(z) = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i)
  31 .fi
  32 .SH VERSIONS
  33 These functions first appeared in glibc in version 2.1.
  34 .SH ATTRIBUTES
  35 For an explanation of the terms used in this section, see
  36 .BR attributes (7).
  37 .TS
  38 allbox;
  39 lbw27 lb lb
  40 l l l.
  41 Interface       Attribute       Value
  42 T{
  43 .BR catan (),
  44 .BR catanf (),
  45 .BR catanl ()
  46 T}      Thread safety   MT-Safe
  47 .TE
  48 .SH CONFORMING TO
  49 C99, POSIX.1-2001, POSIX.1-2008.
  50 .SH EXAMPLE
  51 .EX
  52 /* Link with "\-lm" */
  53
  54 #include <complex.h>
  55 #include <stdlib.h>
  56 #include <unistd.h>
  57 #include <stdio.h>
  58
  59 int
  60 main(int argc, char *argv[])
  61 {
  62     double complex z, c, f;
  63     double complex i = I;
  64
  65     if (argc != 3) {
  66         fprintf(stderr, "Usage: %s <real> <imag>\en", argv[0]);
  67         exit(EXIT_FAILURE);
  68     }
  69
  70     z = atof(argv[1]) + atof(argv[2]) * I;
  71
  72     c = catan(z);
  73     printf("catan() = %6.3f %6.3f*i\en", creal(c), cimag(c));
  74
  75     f = (clog(1 + i * z) \- clog(1 \- i * z)) / (2 * i);
  76     printf("formula = %6.3f %6.3f*i\en", creal(f2), cimag(f2));
  77
  78     exit(EXIT_SUCCESS);
  79 }
  80 .EE
  81 .SH SEE ALSO
  82 .BR ccos (3),
  83 .BR clog (3),
  84 .BR ctan (3),
  85 .BR complex (7)