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add numerical recipes library

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yenru0
2025-09-12 18:55:25 +09:00
parent d4dff245bd
commit 2c75620ec9
1344 changed files with 63869 additions and 0 deletions
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31
lib/nr/k_and_r/recipes/cyclic.c Normal file
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#include "nrutil.h"
void cyclic(a,b,c,alpha,beta,r,x,n)
float a[],alpha,b[],beta,c[],r[],x[];
unsigned long n;
{
void tridag();
unsigned long i;
float fact,gamma,*bb,*u,*z;
if (n <= 2) nrerror("n too small in cyclic");
bb=vector(1,n);
u=vector(1,n);
z=vector(1,n);
gamma = -b[1];
bb[1]=b[1]-gamma;
bb[n]=b[n]-alpha*beta/gamma;
for (i=2;i<n;i++) bb[i]=b[i];
tridag(a,bb,c,r,x,n);
u[1]=gamma;
u[n]=alpha;
for (i=2;i<n;i++) u[i]=0.0;
tridag(a,bb,c,u,z,n);
fact=(x[1]+beta*x[n]/gamma)/
(1.0+z[1]+beta*z[n]/gamma);
for (i=1;i<=n;i++) x[i] -= fact*z[i];
free_vector(z,1,n);
free_vector(u,1,n);
free_vector(bb,1,n);
}