63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
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#define NRANSI
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#include "nrutil.h"
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void mrqmin(float x[], float y[], float sig[], int ndata, float a[], int ia[],
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int ma, float **covar, float **alpha, float *chisq,
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void (*funcs)(float, float [], float *, float [], int), float *alamda)
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{
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void covsrt(float **covar, int ma, int ia[], int mfit);
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void gaussj(float **a, int n, float **b, int m);
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void mrqcof(float x[], float y[], float sig[], int ndata, float a[],
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int ia[], int ma, float **alpha, float beta[], float *chisq,
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void (*funcs)(float, float [], float *, float [], int));
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int j,k,l;
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static int mfit;
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static float ochisq,*atry,*beta,*da,**oneda;
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if (*alamda < 0.0) {
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atry=vector(1,ma);
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beta=vector(1,ma);
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da=vector(1,ma);
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for (mfit=0,j=1;j<=ma;j++)
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if (ia[j]) mfit++;
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oneda=matrix(1,mfit,1,1);
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*alamda=0.001;
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mrqcof(x,y,sig,ndata,a,ia,ma,alpha,beta,chisq,funcs);
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ochisq=(*chisq);
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for (j=1;j<=ma;j++) atry[j]=a[j];
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}
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for (j=1;j<=mfit;j++) {
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for (k=1;k<=mfit;k++) covar[j][k]=alpha[j][k];
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covar[j][j]=alpha[j][j]*(1.0+(*alamda));
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oneda[j][1]=beta[j];
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}
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gaussj(covar,mfit,oneda,1);
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for (j=1;j<=mfit;j++) da[j]=oneda[j][1];
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if (*alamda == 0.0) {
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covsrt(covar,ma,ia,mfit);
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covsrt(alpha,ma,ia,mfit);
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free_matrix(oneda,1,mfit,1,1);
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free_vector(da,1,ma);
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free_vector(beta,1,ma);
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free_vector(atry,1,ma);
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return;
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}
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for (j=0,l=1;l<=ma;l++)
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if (ia[l]) atry[l]=a[l]+da[++j];
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mrqcof(x,y,sig,ndata,atry,ia,ma,covar,da,chisq,funcs);
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if (*chisq < ochisq) {
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*alamda *= 0.1;
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ochisq=(*chisq);
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for (j=1;j<=mfit;j++) {
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for (k=1;k<=mfit;k++) alpha[j][k]=covar[j][k];
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beta[j]=da[j];
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}
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for (l=1;l<=ma;l++) a[l]=atry[l];
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} else {
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*alamda *= 10.0;
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*chisq=ochisq;
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}
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}
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#undef NRANSI
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