cacosh(3)

1cacosh(3)                  Library Functions Manual                  cacosh(3)
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NAME

6       cacosh, cacoshf, cacoshl - complex arc hyperbolic cosine
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LIBRARY

9       Math library (libm, -lm)
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SYNOPSIS

12       #include <complex.h>
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14       double complex cacosh(double complex z);
15       float complex cacoshf(float complex z);
16       long double complex cacoshl(long double complex z);
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DESCRIPTION

19       These  functions  calculate the complex arc hyperbolic cosine of z.  If
20       y = cacosh(z), then z = ccosh(y).  The imaginary part of y is chosen in
21       the interval [-pi,pi].  The real part of y is chosen nonnegative.
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23       One has:
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25           cacosh(z) = 2 * clog(csqrt((z + 1) / 2) + csqrt((z - 1) / 2))
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ATTRIBUTES

28       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
29       tributes(7).
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31       ┌────────────────────────────────────────────┬───────────────┬─────────┐
32       │Interface                                   │ Attribute     │ Value   │
33       ├────────────────────────────────────────────┼───────────────┼─────────┤
34       │cacosh(), cacoshf(), cacoshl()              │ Thread safety │ MT-Safe │
35       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

38       C11, POSIX.1-2008.
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HISTORY

41       C99, POSIX.1-2001.  glibc 2.1.
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EXAMPLES

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