53 lines
1.1 KiB
C++
53 lines
1.1 KiB
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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void NR::gaussj(Mat_IO_DP &a, Mat_IO_DP &b)
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{
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int i,icol,irow,j,k,l,ll;
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DP big,dum,pivinv;
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int n=a.nrows();
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int m=b.ncols();
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Vec_INT indxc(n),indxr(n),ipiv(n);
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for (j=0;j<n;j++) ipiv[j]=0;
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for (i=0;i<n;i++) {
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big=0.0;
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for (j=0;j<n;j++)
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if (ipiv[j] != 1)
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for (k=0;k<n;k++) {
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if (ipiv[k] == 0) {
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if (fabs(a[j][k]) >= big) {
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big=fabs(a[j][k]);
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irow=j;
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icol=k;
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}
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}
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}
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++(ipiv[icol]);
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if (irow != icol) {
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for (l=0;l<n;l++) SWAP(a[irow][l],a[icol][l]);
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for (l=0;l<m;l++) SWAP(b[irow][l],b[icol][l]);
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}
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indxr[i]=irow;
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indxc[i]=icol;
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if (a[icol][icol] == 0.0) nrerror("gaussj: Singular Matrix");
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pivinv=1.0/a[icol][icol];
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a[icol][icol]=1.0;
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for (l=0;l<n;l++) a[icol][l] *= pivinv;
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for (l=0;l<m;l++) b[icol][l] *= pivinv;
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for (ll=0;ll<n;ll++)
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if (ll != icol) {
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dum=a[ll][icol];
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a[ll][icol]=0.0;
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for (l=0;l<n;l++) a[ll][l] -= a[icol][l]*dum;
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for (l=0;l<m;l++) b[ll][l] -= b[icol][l]*dum;
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}
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}
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for (l=n-1;l>=0;l--) {
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if (indxr[l] != indxc[l])
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for (k=0;k<n;k++)
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SWAP(a[k][indxr[l]],a[k][indxc[l]]);
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}
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}
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