catan man page

catan, catanf, catanl — complex arc tangents

Synopsis

#include <complex.h>

double complex catan(double complex z);
float complex catanf(float complex z);
long double complex catanl(long double complex z);

Link with -lm.

Description

These functions calculate the complex arc tangent of z. If y = catan(z), then z = ctan(y). The real part of y is chosen in the interval [-pi/2,pi/2].

One has:

    catan(z) = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i)

Versions

These functions first appeared in glibc in version 2.1.

Attributes

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
catan(), catanf(), catanl() Thread safety MT-Safe

Conforming to

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

Example

/* Link with "-lm" */

#include <complex.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>

int
main(int argc, char *argv[])
{
    double complex z, c, f;
    double complex i = I;

    if (argc != 3) {
        fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    z = atof(argv[1]) + atof(argv[2]) * I;

    c = catan(z);
    printf("catan() = %6.3f %6.3f*i\n", creal(c), cimag(c));

    f = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i);
    printf("formula = %6.3f %6.3f*i\n", creal(f2), cimag(f2));

    exit(EXIT_SUCCESS);
}

See Also

ccos(3), clog(3), ctan(3), complex(7)

Colophon

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Referenced By

atan(3), complex(7), ctan(3).

catanf(3) and catanl(3) are aliases of catan(3).

2015-04-19 Linux Programmer's Manual