89 lines
2.0 KiB
C
89 lines
2.0 KiB
C
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/* Driver for routine gaussj */
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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 MP 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;
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float **a,**ai,**u,**b,**x,**t;
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char dummy[MAXSTR];
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FILE *fp;
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a=matrix(1,NP,1,NP);
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ai=matrix(1,NP,1,NP);
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u=matrix(1,NP,1,NP);
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b=matrix(1,NP,1,MP);
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x=matrix(1,NP,1,MP);
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t=matrix(1,NP,1,MP);
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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 matrices for later testing of results */
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for (l=1;l<=n;l++) {
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for (k=1;k<=n;k++) ai[k][l]=a[k][l];
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for (k=1;k<=m;k++) x[l][k]=b[l][k];
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}
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/* invert matrix */
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gaussj(ai,n,x,m);
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printf("\nInverse of matrix a : \n");
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for (k=1;k<=n;k++) {
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for (l=1;l<=n;l++) printf("%12.6f",ai[k][l]);
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printf("\n");
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}
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/* check inverse */
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printf("\na times a-inverse:\n");
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for (k=1;k<=n;k++) {
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for (l=1;l<=n;l++) {
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u[k][l]=0.0;
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for (j=1;j<=n;j++)
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u[k][l] += (a[k][j]*ai[j][l]);
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}
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for (l=1;l<=n;l++) printf("%12.6f",u[k][l]);
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printf("\n");
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}
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/* check vector solutions */
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printf("\nCheck the following for equality:\n");
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printf("%21s %14s\n","original","matrix*sol'n");
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for (l=1;l<=m;l++) {
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printf("vector %2d: \n",l);
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for (k=1;k<=n;k++) {
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t[k][l]=0.0;
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for (j=1;j<=n;j++)
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t[k][l] += (a[k][j]*x[j][l]);
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printf("%8s %12.6f %12.6f\n"," ",
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b[k][l],t[k][l]);
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}
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}
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printf("***********************************\n");
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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(t,1,NP,1,MP);
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free_matrix(x,1,NP,1,MP);
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free_matrix(b,1,NP,1,MP);
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free_matrix(u,1,NP,1,NP);
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free_matrix(ai,1,NP,1,NP);
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free_matrix(a,1,NP,1,NP);
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return 0;
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}
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#undef NRANSI
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