44 lines
952 B
C
44 lines
952 B
C
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/* Driver for routine mgfas */
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#include <stdio.h>
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#include <math.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 NSTEP 4
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#define JMAX 33
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int main(void)
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{
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int i,j,midl=JMAX/2+1;
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double **f,**u;
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f=dmatrix(1,JMAX,1,JMAX);
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u=dmatrix(1,JMAX,1,JMAX);
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for (i=1;i<=JMAX;i++)
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for (j=1;j<=JMAX;j++)
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u[i][j]=0.0;
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u[midl][midl]=2.0;
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mgfas(u,JMAX,2);
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printf("MGFAS solution:\n");
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for (i=1;i<=JMAX;i+=NSTEP) {
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for (j=1;j<=JMAX;j+=NSTEP) printf("%8.4f",u[i][j]);
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printf("\n");
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}
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printf("\n Test that solution satisfies difference equations:\n");
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for (i=NSTEP+1;i<JMAX;i+=NSTEP) {
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for (j=NSTEP+1;j<JMAX;j+=NSTEP)
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f[i][j]=u[i+1][j]+u[i-1][j]+u[i][j+1]+u[i][j-1]-
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4.0*u[i][j]+u[i][j]*u[i][j]/((JMAX-1)*(JMAX-1));
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printf("%7s"," ");
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for (j=NSTEP+1;j<JMAX;j+=NSTEP) printf("%8.4f",f[i][j]*(JMAX-1)*(JMAX-1));
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printf("\n");
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}
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free_dmatrix(u,1,JMAX,1,JMAX);
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free_dmatrix(f,1,JMAX,1,JMAX);
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return 0;
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}
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#undef NRANSI
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