min_parabol.c
No OneTemporary
Actions

Subscribers

None

File Metadata

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


	/****************************************************************/
	/* nom: min_parabol */
	/* auteur: Jean-Paul Kneib */
	/* date: 10/02/92 */
	/* place: Toulouse */
	/* */
	/* recherche d'un minimum dans le cas ou on a 3 points */
	/* tels que (x1<x0<x2 ou x1>x0>x2) et (y0<y1<y2 ou y1>y2>y0) */
	/****************************************************************/

	double min_parabol(double x0, double y0, double x1, double y1, double x2, double y2)
	{
	const extern struct g_mode M;
	double D1, D2, a, xmin;


	D1 = slope(x0, y0, x1, y1);
	D2 = slope(x0, y0, x2, y2);

	if (D1*D2 > 0.)
	{
	NPRINTF(stderr, "ERROR: x0 not an estimated minimum");
	NPRINTF(stderr, "\t%lf %lf %lf %lf %lf %lf %.3lf %.3lf\n",
	x0, y0, x1, y1, x2, y2, D1, D2);
	return(x0);
	};
	if (D1 == 0.)
	xmin = .5 * (x0 + x1);
	else if (D2 == 0.)
	xmin = .5 * (x0 + x2);
	else
	{
	a = slope(x1, D1, x2, D2);
	xmin = .5 * (x0 + .5 * (x1 + x2 - (D1 + D2) / a));
	};
	return(xmin);
	}