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 y = ca‐
19       cos(z), then z = ccos(y).  The real part of y is chosen in the interval
20       [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 at‐
31       tributes(7).
32
33       ┌────────────────────────────────────────────┬───────────────┬─────────┐
34       │Interface                                   │ Attribute     │ Value   │
35       ├────────────────────────────────────────────┼───────────────┼─────────┤
36       │cacos(), cacosf(), cacosl()                 │ Thread safety │ MT-Safe │
37       └────────────────────────────────────────────┴───────────────┴─────────┘
38

CONFORMING TO

40       C99, POSIX.1-2001, POSIX.1-2008.
41

EXAMPLES

43       /* Link with "-lm" */
44
45       #include <complex.h>
46       #include <stdlib.h>
47       #include <unistd.h>
48       #include <stdio.h>
49
50       int
51       main(int argc, char *argv[])
52       {
53           double complex z, c, f;
54           double complex i = I;
55
56           if (argc != 3) {
57               fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
58               exit(EXIT_FAILURE);
59           }
60
61           z = atof(argv[1]) + atof(argv[2]) * I;
62
63           c = cacos(z);
64
65           printf("cacos() = %6.3f %6.3f*i\n", creal(c), cimag(c));
66
67           f = -i * clog(z + i * csqrt(1 - z * z));
68
69           printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f));
70
71           exit(EXIT_SUCCESS);
72       }
73

COLOPHON

78       This page is part of release 5.12 of the Linux  man-pages  project.   A
79       description  of  the project, information about reporting bugs, and the
80       latest    version    of    this    page,    can     be     found     at
81       https://www.kernel.org/doc/man-pages/.
82
83
84
85                                  2021-03-22                          CACOS(3)