catan(3) - BetterMan

catan(3)

complex arc tangents

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Synopsis

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

—

NAME

catan, catanf, catanl - complex arc tangents

LIBRARY

Math library (libm, -lm)

SYNOPSIS

bash

#include <complex.h>

bash

double complex catan(double complex \nz\n);\n
\nfloat complex catanf(float complex \nz\n);\n
\nlong double complex catanl(long double complex \nz\n);

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:

bash

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).

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

STANDARDS

C11, POSIX.1-2008.

HISTORY

glibc 2.1. C99, POSIX.1-2001.

EXAMPLES

bash

/* Link with "-lm" */
#include <complex.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
\n
    double complex z, c, f;
\n
    double complex i = I;
\n
    if (argc != 3) {
\n
        fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
\n
        exit(EXIT_FAILURE);
\n
    }
\n
    z = atof(argv[1]) + atof(argv[2]) * I;
\n
    c = catan(z);
\n
    printf("catan() = %6.3f %6.3f*i\n", creal(c), cimag(c));
\n
    f = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i);
\n
    printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f));
\n
    exit(EXIT_SUCCESS);
}