73 lines
1.6 KiB
C
73 lines
1.6 KiB
C
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/* Driver for routine lubksb */
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#include <stdio.h>
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#include <stdlib.h>
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#define NRANSI
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#include "nr.h"
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#include "nrutil.h"
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#define NP 20
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#define MAXSTR 80
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int main(void)
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{
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int j,k,l,m,n,*indx;
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float p,*x,**a,**b,**c;
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char dummy[MAXSTR];
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FILE *fp;
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indx=ivector(1,NP);
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x=vector(1,NP);
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a=matrix(1,NP,1,NP);
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b=matrix(1,NP,1,NP);
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c=matrix(1,NP,1,NP);
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if ((fp = fopen("matrx1.dat","r")) == NULL)
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nrerror("Data file matrx1.dat not found\n");
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while (!feof(fp)) {
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fgets(dummy,MAXSTR,fp);
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fgets(dummy,MAXSTR,fp);
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fscanf(fp,"%d %d ",&n,&m);
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fgets(dummy,MAXSTR,fp);
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for (k=1;k<=n;k++)
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for (l=1;l<=n;l++) fscanf(fp,"%f ",&a[k][l]);
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fgets(dummy,MAXSTR,fp);
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for (l=1;l<=m;l++)
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for (k=1;k<=n;k++) fscanf(fp,"%f ",&b[k][l]);
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/* Save matrix a for later testing */
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for (l=1;l<=n;l++)
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for (k=1;k<=n;k++) c[k][l]=a[k][l];
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/* Do LU decomposition */
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ludcmp(c,n,indx,&p);
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/* Solve equations for each right-hand vector */
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for (k=1;k<=m;k++) {
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for (l=1;l<=n;l++) x[l]=b[l][k];
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lubksb(c,n,indx,x);
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/* Test results with original matrix */
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printf("right-hand side vector:\n");
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for (l=1;l<=n;l++)
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printf("%12.6f",b[l][k]);
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printf("\n%s%s\n","result of matrix applied",
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" to sol'n vector");
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for (l=1;l<=n;l++) {
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b[l][k]=0.0;
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for (j=1;j<=n;j++)
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b[l][k] += (a[l][j]*x[j]);
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}
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for (l=1;l<=n;l++)
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printf("%12.6f",b[l][k]);
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printf("\n*********************************\n");
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}
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printf("press RETURN for next problem:\n");
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(void) getchar();
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}
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fclose(fp);
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free_matrix(c,1,NP,1,NP);
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free_matrix(b,1,NP,1,NP);
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free_matrix(a,1,NP,1,NP);
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free_vector(x,1,NP);
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free_ivector(indx,1,NP);
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return 0;
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}
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#undef NRANSI
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