NAME¶

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).

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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