60 lines
1.3 KiB
C++
60 lines
1.3 KiB
C++
#include "nr.h"
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void NR::lfit(Vec_I_DP &x, Vec_I_DP &y, Vec_I_DP &sig, Vec_IO_DP &a,
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Vec_I_BOOL &ia, Mat_O_DP &covar, DP &chisq,
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void funcs(const DP, Vec_O_DP &))
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{
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int i,j,k,l,m,mfit=0;
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DP ym,wt,sum,sig2i;
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int ndat=x.size();
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int ma=a.size();
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Vec_DP afunc(ma);
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Mat_DP beta(ma,1);
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for (j=0;j<ma;j++)
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if (ia[j]) mfit++;
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if (mfit == 0) nrerror("lfit: no parameters to be fitted");
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for (j=0;j<mfit;j++) {
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for (k=0;k<mfit;k++) covar[j][k]=0.0;
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beta[j][0]=0.0;
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}
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for (i=0;i<ndat;i++) {
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funcs(x[i],afunc);
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ym=y[i];
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if (mfit < ma) {
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for (j=0;j<ma;j++)
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if (!ia[j]) ym -= a[j]*afunc[j];
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}
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sig2i=1.0/SQR(sig[i]);
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for (j=0,l=0;l<ma;l++) {
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if (ia[l]) {
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wt=afunc[l]*sig2i;
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for (k=0,m=0;m<=l;m++)
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if (ia[m]) covar[j][k++] += wt*afunc[m];
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beta[j++][0] += ym*wt;
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}
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}
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}
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for (j=1;j<mfit;j++)
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for (k=0;k<j;k++)
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covar[k][j]=covar[j][k];
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Mat_DP temp(mfit,mfit);
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for (j=0;j<mfit;j++)
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for (k=0;k<mfit;k++)
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temp[j][k]=covar[j][k];
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gaussj(temp,beta);
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for (j=0;j<mfit;j++)
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for (k=0;k<mfit;k++)
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covar[j][k]=temp[j][k];
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for (j=0,l=0;l<ma;l++)
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if (ia[l]) a[l]=beta[j++][0];
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chisq=0.0;
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for (i=0;i<ndat;i++) {
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funcs(x[i],afunc);
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sum=0.0;
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for (j=0;j<ma;j++) sum += a[j]*afunc[j];
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chisq += SQR((y[i]-sum)/sig[i]);
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}
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covsrt(covar,ia,mfit);
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}
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