chsigne.c
c99f2e455a51gridgradient_gilles

chsigne.c
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			#include<stdio.h>
			#include<math.h>
			#include<fonction.h>
			#include<constant.h>
			#include<dimension.h>
			#include<structure.h>

			/****************************************************************/
			/* nom: chsigne */
			/* auteur: Jean-Paul Kneib */
			/* date: 10/02/92 */
			/* place: Toulouse */
			/*****************************************************************
			* Return 0 if A and B are on the same side of a critical line
			* If A and B are on each side of a critical line then
			* if A or B have 2 positive partial parities then Return 1 (radial CL)
			* else Return 2 (tangential CL)
			*
			* Global variables used :
			* - in e_unmag() : G, lens
			*/
			int chsigne( struct point A, struct point B, double dl0s, double dos, double zs )
			{
			struct ellipse ampa, ampb;
			double sa, sb; /total parities of A and B/

			ampa = e_unmag(&A, dl0s, dos, zs);
			ampb = e_unmag(&B, dl0s, dos, zs);
			sa = ampa.a * ampa.b;
			sb = ampb.a * ampb.b;

			if (sa*sb >= 0.)
			return(0);
			else
			{
			if ( ((sa > 0.) && (ampa.a > 0.)) \|\| ((sb > 0.) && (ampb.a > 0.)) )
			return(1);
			else
			return(2);
			};
			}