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);

       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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       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
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				  2015-04-19			      CATAN(3)