# catan(3) [minix man page]

```CATAN(3)						     Linux Programmer's Manual							  CATAN(3)

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);

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

#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>
", argv[0]);
exit(EXIT_FAILURE);
}

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

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

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

exit(EXIT_SUCCESS);
}

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

COLOPHON
This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the

2015-04-19								  CATAN(3)```

## Check Out this Related Man Page

```CATAN(3)						     Linux Programmer's Manual							  CATAN(3)

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);

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

#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>
", argv[0]);
exit(EXIT_FAILURE);
}

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

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

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

exit(EXIT_SUCCESS);
}