/*                                                                           */
/*            Copyright (C)           1999-2023         M. Held              */
/*                                                                           */
/* This code is not in the public domain. All rights reserved! Please make   */
/* sure to read the full copyright statement contained in "README.txt" or in */
/* the "main" file of this code, such as "main.cc".                          */
/*                                                                           */
/*****************************************************************************/
/*                                                                           */
/* Written by:  Martin Held                                                  */
/*                                                                           */
/* E-Mail:      held@cs.sbg.ac.at                                            */
/* Fax Mail:    (+43 662) 8044-611                                           */
/* Voice Mail:  (+43 662) 8044-6304                                          */
/* Snail Mail:  Martin Held                                                  */
/*              FB Informatik                                                */
/*              Universitaet Salzburg                                        */
/*              A-5020 Salzburg, Austria                                     */
/*                                                                           */
/*****************************************************************************/

#ifndef VRONI_CORE_ATAN2_H
#define VRONI_CPRE_ATAN2_H


inline double atan2local(const double &y, const double &x) 
{
	if( fabs(x) >= fabs(y) )
	{
		// Sector to the right
		if( x > 0 )
		{
			const double phi = y/x;
			return atan(phi);
		}
		// Sector to the left
		else if( x < 0 )
		{
			const double phi = y/x;
			if( y >= 0) {
				return  atan(phi) + M_PI;
			} else {
				return atan(phi) - M_PI;
			}
		}
		// Hence, x and y are zero
		else
		{
			return 0.0;
		}
	}
	else if( fabs(y) >= fabs(x) )
	{
		// Sector to the top
		if( y > 0 )
		{
			const double phi = x/y;
			return M_PI_2 - atan(phi);
		}
		// Sector to the bottom
		if( y < 0 )
		{
			const double phi = x/y;
			return - M_PI_2 - atan(phi);
		}
		// Actually, the impossible case, x=y=0. Should be catched above.
		else
		{
			assert(false);
			return 0.0;
		}

	}
	// This can only happen, if x or y is NaN.
	else
	{
		return 0.0;
	}
}

#endif