/************************************************************************
 *									*
 *				N O T I C E				*
 *									*
 *			Copyright Abandoned, 1987, Fred Fish		*
 *									*
 *	This previously copyrighted work has been placed into the	*
 *	public domain by the author (Fred Fish) and may be freely used	*
 *	for any purpose, private or commercial.  I would appreciate	*
 *	it, as a courtesy, if this notice is left in all copies and	*
 *	derivative works.  Thank you, and enjoy...			*
 *									*
 *	The author makes no warranty of any kind with respect to this	*
 *	product and explicitly disclaims any implied warranties of	*
 *	merchantability or fitness for any particular purpose.		*
 *									*
 ************************************************************************
 */


/*
 *  FUNCTION
 *
 *	ctan   complex double precision tangent
 *
 *  KEY WORDS
 *
 *	ctan
 *	complex functions
 *	machine independent functions
 *	math libraries
 *
 *  DESCRIPTION
 *
 *	Computes double precision complex tangent of a double
 *	precision complex argument.
 *
 *  USAGE
 *
 *	COMPLEX ctan (z)
 *	COMPLEX z;
 *
 *  PROGRAMMER
 *
 *	Fred Fish
 *	Tempe, Az 85281
 *	(602) 966-8871
 *
 *  INTERNALS
 *
 *	Computes complex tangent of z = x + j y from:
 *
 *		1.	Compute ccos(z)
 *
 *		2.	If ccos(z) = 0 + j0 then the
 *			result is MAX_POS_DBLF + j0
 *
 *		3.	Else ctan(z) = csin(z) / ccos(z)
 *
 */

#if defined (__M68881__) && !defined (_M68881)
/*# define _M68881*/
#endif

#include <stdio.h>
#include <math.h>
#include "pml.h"

COMPLEX ctan (z)
COMPLEX z;
{
    COMPLEX ccosz,csinz;
    double  denom;

    ccosz = ccos (z);
    csinz = csin (z);

    if (ccosz.real == 0.0 && ccosz.imag == 0.0) {
#ifdef	ERROR_CHECK
	fputs (stderr, " ctan: SINGULARITY\n");
	errno = ERANGE;		/* should be EDOM if csinz.real or csinz.imag == 0	*/

	if( csinz.real >= 0.0)	z.real = HUGE_VAL;	
					/* still wrong, == 0 should yield NAN */
	else			z.real = -HUGE_VAL;	
	if( csinz.imag >= 0.0) 	z.imag = HUGE_VAL;
					/* still wrong, == 0 should yield NAN */
	else			z.imag = -HUGE_VAL;	
#else	ERROR_CHECK
	z = cdiv(csinz,ccosz);
#endif	ERROR_CHECK
    } else {
	z = cdiv(csinz,ccosz);
    }
    return (z);
}