catan(3)

1CATAN(3)                   Linux Programmer's Manual                  CATAN(3)
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NAME

6       catan, catanf, catanl - complex arc tangents
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SYNOPSIS

9       #include <complex.h>
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11       double complex catan(double complex z);
12       float complex catanf(float complex z);
13       long double complex catanl(long double complex z);
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15       Link with -lm.
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DESCRIPTION

18       The  catan()  function  calculates  the  complex  arc tangent of z.  If
19       y = catan(z), then z = ctan(y).  The real part of y is  chosen  in  the
20       interval [-pi/2,pi/2].
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22       One has:
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24           catan(z) = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i)
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VERSIONS

27       These functions first appeared in glibc in version 2.1.
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CONFORMING TO

30       C99.
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EXAMPLE

33       /* Link with "-lm" */
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35       #include <complex.h>
36       #include <stdlib.h>
37       #include <unistd.h>
38       #include <stdio.h>
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40       int
41       main(int argc, char *argv[])
42       {
43           double complex z, c, f;
44           double complex i = I;
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46           if (argc != 3) {
47               fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
48               exit(EXIT_FAILURE);
49           }
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51           z = atof(argv[1]) + atof(argv[2]) * I;
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53           c = catan(z);
54           printf("catan() = %6.3f %6.3f*i\n", creal(c), cimag(c));
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56           f = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i);
57           printf("formula = %6.3f %6.3f*i\n", creal(f2), cimag(f2));
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59           exit(EXIT_SUCCESS);
60       }
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COLOPHON

66       This  page  is  part of release 3.53 of the Linux man-pages project.  A
67       description of the project, and information about reporting  bugs,  can
68       be found at http://www.kernel.org/doc/man-pages/.
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72                                  2011-09-15                          CATAN(3)