catan(3) - f34

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       These   functions   calculate   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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ATTRIBUTES

30       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
31       tributes(7).
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33       ┌────────────────────────────┬───────────────┬─────────┐
34       │Interface                   │ Attribute     │ Value   │
35       ├────────────────────────────┼───────────────┼─────────┤
36       │catan(), catanf(), catanl() │ Thread safety │ MT-Safe │
37       └────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

39       C99, POSIX.1-2001, POSIX.1-2008.
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EXAMPLES

42       /* Link with "-lm" */
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44       #include <complex.h>
45       #include <stdlib.h>
46       #include <unistd.h>
47       #include <stdio.h>
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49       int
50       main(int argc, char *argv[])
51       {
52           double complex z, c, f;
53           double complex i = I;
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55           if (argc != 3) {
56               fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
57               exit(EXIT_FAILURE);
58           }
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60           z = atof(argv[1]) + atof(argv[2]) * I;
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62           c = catan(z);
63           printf("catan() = %6.3f %6.3f*i\n", creal(c), cimag(c));
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65           f = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i);
66           printf("formula = %6.3f %6.3f*i\n", creal(f2), cimag(f2));
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68           exit(EXIT_SUCCESS);
69       }
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COLOPHON

75       This page is part of release 5.10 of the Linux  man-pages  project.   A
76       description  of  the project, information about reporting bugs, and the
77       latest    version    of    this    page,    can     be     found     at
78       https://www.kernel.org/doc/man-pages/.
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82                                  2020-06-09                          CATAN(3)