34 lines
757 B
C
34 lines
757 B
C
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#define NRANSI
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#include "nrutil.h"
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void cyclic(float a[], float b[], float c[], float alpha, float beta,
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float r[], float x[], unsigned long n)
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{
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void tridag(float a[], float b[], float c[], float r[], float u[],
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unsigned long n);
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unsigned long i;
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float fact,gamma,*bb,*u,*z;
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if (n <= 2) nrerror("n too small in cyclic");
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bb=vector(1,n);
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u=vector(1,n);
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z=vector(1,n);
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gamma = -b[1];
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bb[1]=b[1]-gamma;
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bb[n]=b[n]-alpha*beta/gamma;
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for (i=2;i<n;i++) bb[i]=b[i];
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tridag(a,bb,c,r,x,n);
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u[1]=gamma;
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u[n]=alpha;
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for (i=2;i<n;i++) u[i]=0.0;
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tridag(a,bb,c,u,z,n);
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fact=(x[1]+beta*x[n]/gamma)/
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(1.0+z[1]+beta*z[n]/gamma);
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for (i=1;i<=n;i++) x[i] -= fact*z[i];
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free_vector(z,1,n);
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free_vector(u,1,n);
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free_vector(bb,1,n);
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}
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#undef NRANSI
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