/* @(#)mrqcof.c	17.1.1.1 (ES0-DMD) 01/25/02 17:27:00 */
/*===========================================================================
  Copyright (C) 1995 European Southern Observatory (ESO)
 
  This program is free software; you can redistribute it and/or 
  modify it under the terms of the GNU General Public License as 
  published by the Free Software Foundation; either version 2 of 
  the License, or (at your option) any later version.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public 
  License along with this program; if not, write to the Free 
  Software Foundation, Inc., 675 Massachusetss Ave, Cambridge, 
  MA 02139, USA.
 
  Corresponding concerning ESO-MIDAS should be addressed as follows:
	Internet e-mail: midas@eso.org
	Postal address: European Southern Observatory
			Data Management Division 
			Karl-Schwarzschild-Strasse 2
			D 85748 Garching bei Muenchen 
			GERMANY
===========================================================================*/

/* @(#)mrqcof.c	17.1.1.1  (ESO)  01/25/02  17:27:00 */

void mrqcof(x,y,sig,ndata,a,ma,lista,mfit,alpha,beta,chisq,funcs)
float x[],y[];
double sig[],a[],**alpha,beta[],*chisq;
int ndata,ma,lista[],mfit;
void (*funcs)();	/* ANSI: void (*funcs)(float,float *,float *,float *,int); */
{
	int k,j,i;
	double wt,sig2i,dy,*dyda,*dvector();
	float ymod;
	void free_dvector();
	dyda=dvector(1,ma);
	for (j=1;j<=mfit;j++) {
		for (k=1;k<=j;k++) alpha[j][k]=0.0;
		beta[j]=0.0;
	}
	*chisq=0.0;
	for (i=1;i<=ndata;i++) {
		(*funcs)(x[i],a,&ymod,dyda,ma);
		sig2i=1.0/(sig[i]*sig[i]);
		dy=(double)(y[i]-ymod);
		for (j=1;j<=mfit;j++) {
			wt=dyda[lista[j]]*sig2i;
			for (k=1;k<=j;k++)
				alpha[j][k] += wt*dyda[lista[k]];
			beta[j] += dy*wt;
		}
		(*chisq) += dy*dy*sig2i;
	}
	for (j=2;j<=mfit;j++)
		for (k=1;k<=j-1;k++) alpha[k][j]=alpha[j][k];
	free_dvector(dyda,1,ma);
}