catan(3) Linux Man Page - System Grab Bag

Name

catan, catanf, catanl - complex arc tangents

Library

Math library ( libm ", " -lm )

Synopsis

#include <complex.h> 
double complex catan(double complex  z );
float complex catanf(float complex  z );
long double complex catanl(long double complex  z );

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)

Attributes

For an explanation of the terms used in this section, see attributes(7). allbox; lbx lb lb T{ catan()catanf()catanl()

Interface	Attribute	Value
T}	Thread safety	MT-Safe

Standards

C11, POSIX.1-2008.

History

glibc 2.1. C99, POSIX.1-2001.

Examples

/* Link with "-lm" */

#include <complex.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.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>\en", argv[0]);
        exit(EXIT_FAILURE);
    }

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

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

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

    exit(EXIT_SUCCESS);
}