cacosf(3)

1CACOS(3)                   Linux Programmer's Manual                  CACOS(3)
2
3
4

NAME

6       cacos, cacosf, cacosl - complex arc cosine
7

SYNOPSIS

9       #include <complex.h>
10
11       double complex cacos(double complex z);
12       float complex cacosf(float complex z);
13       long double complex cacosl(long double complex z);
14
15       Link with -lm.
16

DESCRIPTION

18       These   functions   calculate   the   complex  arc  cosine  of  z.   If
19       y = cacos(z), then z = ccos(y).  The real part of y is  chosen  in  the
20       interval [0,pi].
21
22       One has:
23
24           cacos(z) = -i * clog(z + i * csqrt(1 - z * z))
25

VERSIONS

27       These functions first appeared in glibc in version 2.1.
28

ATTRIBUTES

30       For   an   explanation   of   the  terms  used  in  this  section,  see
31       attributes(7).
32
33       ┌─────────────────────────────┬───────────────┬─────────┐
34       │Interface                    │ Attribute     │ Value   │
35       ├─────────────────────────────┼───────────────┼─────────┤
36       │cacos(), cacosf(), cacosl()  │ Thread safety │ MT-Safe │
37       └─────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

39       C99, POSIX.1-2001, POSIX.1-2008.
40

EXAMPLE

42       /* Link with "-lm" */
43
44       #include <complex.h>
45       #include <stdlib.h>
46       #include <unistd.h>
47       #include <stdio.h>
48
49       int
50       main(int argc, char *argv[])
51       {
52           double complex z, c, f;
53           double complex i = I;
54
55           if (argc != 3) {
56               fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
57               exit(EXIT_FAILURE);
58           }
59
60           z = atof(argv[1]) + atof(argv[2]) * I;
61
62           c = cacos(z);
63
64           printf("cacos() = %6.3f %6.3f*i\n", creal(c), cimag(c));
65
66           f = -i * clog(z + i * csqrt(1 - z * z));
67
68           printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f));
69
70           exit(EXIT_SUCCESS);
71       }
72

COLOPHON

77       This page is part of release 5.02 of the Linux  man-pages  project.   A
78       description  of  the project, information about reporting bugs, and the
79       latest    version    of    this    page,    can     be     found     at
80       https://www.kernel.org/doc/man-pages/.
81
82
83
84                                  2019-03-06                          CACOS(3)