67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
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/* Driver for routine tred2 */
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#include <stdio.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 10
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int main(void)
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{
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int i,j,k,l,m;
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float *d,*e,**a,**f;
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static float c[NP][NP]={
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5.0, 4.3, 3.0, 2.0, 1.0, 0.0,-1.0,-2.0,-3.0,-4.0,
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4.3, 5.1, 4.0, 3.0, 2.0, 1.0, 0.0,-1.0,-2.0,-3.0,
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3.0, 4.0, 5.0, 4.0, 3.0, 2.0, 1.0, 0.0,-1.0,-2.0,
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2.0, 3.0, 4.0, 5.0, 4.0, 3.0, 2.0, 1.0, 0.0,-1.0,
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1.0, 2.0, 3.0, 4.0, 5.0, 4.0, 3.0, 2.0, 1.0, 0.0,
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0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 4.0, 3.0, 2.0, 1.0,
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-1.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 4.0, 3.0, 2.0,
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-2.0,-1.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 4.0, 3.0,
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-3.0,-2.0,-1.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 4.0,
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-4.0,-3.0,-2.0,-1.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0};
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d=vector(1,NP);
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e=vector(1,NP);
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a=matrix(1,NP,1,NP);
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f=matrix(1,NP,1,NP);
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for (i=1;i<=NP;i++)
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for (j=1;j<=NP;j++) a[i][j]=c[i-1][j-1];
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tred2(a,NP,d,e);
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printf("diagonal elements\n");
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for (i=1;i<=NP;i++) {
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printf("%12.6f",d[i]);
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if ((i % 5) == 0) printf("\n");
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}
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printf("off-diagonal elements\n");
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for (i=2;i<=NP;i++) {
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printf("%12.6f",e[i]);
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if ((i % 5) == 0) printf("\n");
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}
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/* Check transformation matrix */
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for (j=1;j<=NP;j++) {
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for (k=1;k<=NP;k++) {
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f[j][k]=0.0;
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for (l=1;l<=NP;l++) {
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for (m=1;m<=NP;m++)
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f[j][k] += a[l][j]*c[l-1][m-1]*a[m][k];
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}
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}
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}
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/* How does it look? */
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printf("tridiagonal matrix\n");
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for (i=1;i<=NP;i++) {
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for (j=1;j<=NP;j++) printf("%7.2f",f[i][j]);
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printf("\n");
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}
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free_matrix(f,1,NP,1,NP);
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free_matrix(a,1,NP,1,NP);
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free_vector(e,1,NP);
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free_vector(d,1,NP);
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return 0;
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}
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#undef NRANSI
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