Category : C Source Code
Archive   : RECIPEX.ZIP
Filename : SPARSE.C

 
Output of file : SPARSE.C contained in archive : RECIPEX.ZIP
#define EPS 1.0e-6
#define FREERETURN {free_vector(xj,1,n);free_vector(xi,1,n);\
free_vector(h,1,n);free_vector(g,1,n);return;}

void sparse(b,n,x,rsq)
float b[],x[],*rsq;
int n;
{
int j,iter,irst=0;
float aden,anum,bsq,dgg,eps2,gam,gg,rp;
float *g,*h,*xi,*xj,*vector();
void asub(),atsub(),nrerror(),free_vector();

g=vector(1,n);
h=vector(1,n);
xi=vector(1,n);
xj=vector(1,n);
eps2=n*EPS*EPS;
for (;;) {
++irst;
asub(x,xi,n);
rp=bsq=0.0;
for (j=1;j<=n;j++) {
bsq += b[j]*b[j];
xi[j] -= b[j];
rp += xi[j]*xi[j];
}
atsub(xi,g,n);
for (j=1;j<=n;j++)
h[j] = g[j] = -g[j];
for (iter=1;iter<=10*n;iter++) {
asub(h,xi,n);
anum=aden=0.0;
for (j=1;j<=n;j++) {
anum += g[j]*h[j];
aden += xi[j]*xi[j];
}
if (aden == 0.0) nrerror("Very singular matrix in SPARSE");
anum /= aden;
for (j=1;j<=n;j++) {
xi[j]=x[j];
x[j] += anum*h[j];
}
asub(x,xj,n);
*rsq=0.0;
for (j=1;j<=n;j++) {
xj[j] -= b[j];
*rsq += xj[j]*xj[j];
}
if (*rsq == rp || *rsq <= bsq*eps2) FREERETURN
if (*rsq > rp) {
for (j=1;j<=n;j++) x[j]=xi[j];
if (irst >= 3) FREERETURN
break;
}
rp = *rsq;
atsub(xj,xi,n);
gg=dgg=0.0;
for (j=1;j<=n;j++) {
gg += g[j]*g[j];
dgg += (xi[j]+g[j])*xi[j];
}
if (gg == 0.0) FREERETURN
gam=dgg/gg;
for (j=1;j<=n;j++) {
g[j] = -xi[j];
h[j]=g[j]+gam*h[j];
}
}
nrerror("Too many interations in routine SPARSE");
}
}

#undef EPS
#undef FREERETURN


  3 Responses to “Category : C Source Code
Archive   : RECIPEX.ZIP
Filename : SPARSE.C

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/