#include #define NRANSI #include "nrutil.h" #define ROTATE(a,i,j,k,l) g=a[i][j];h=a[k][l];a[i][j]=g-s*(h+g*tau);\ a[k][l]=h+s*(g-h*tau); void jacobi(float **a, int n, float d[], float **v, int *nrot) { int j,iq,ip,i; float tresh,theta,tau,t,sm,s,h,g,c,*b,*z; b=vector(1,n); z=vector(1,n); for (ip=1;ip<=n;ip++) { for (iq=1;iq<=n;iq++) v[ip][iq]=0.0; v[ip][ip]=1.0; } for (ip=1;ip<=n;ip++) { b[ip]=d[ip]=a[ip][ip]; z[ip]=0.0; } *nrot=0; for (i=1;i<=50;i++) { sm=0.0; for (ip=1;ip<=n-1;ip++) { for (iq=ip+1;iq<=n;iq++) sm += fabs(a[ip][iq]); } if (sm == 0.0) { free_vector(z,1,n); free_vector(b,1,n); return; } if (i < 4) tresh=0.2*sm/(n*n); else tresh=0.0; for (ip=1;ip<=n-1;ip++) { for (iq=ip+1;iq<=n;iq++) { g=100.0*fabs(a[ip][iq]); if (i > 4 && (float)(fabs(d[ip])+g) == (float)fabs(d[ip]) && (float)(fabs(d[iq])+g) == (float)fabs(d[iq])) a[ip][iq]=0.0; else if (fabs(a[ip][iq]) > tresh) { h=d[iq]-d[ip]; if ((float)(fabs(h)+g) == (float)fabs(h)) t=(a[ip][iq])/h; else { theta=0.5*h/(a[ip][iq]); t=1.0/(fabs(theta)+sqrt(1.0+theta*theta)); if (theta < 0.0) t = -t; } c=1.0/sqrt(1+t*t); s=t*c; tau=s/(1.0+c); h=t*a[ip][iq]; z[ip] -= h; z[iq] += h; d[ip] -= h; d[iq] += h; a[ip][iq]=0.0; for (j=1;j<=ip-1;j++) { ROTATE(a,j,ip,j,iq) } for (j=ip+1;j<=iq-1;j++) { ROTATE(a,ip,j,j,iq) } for (j=iq+1;j<=n;j++) { ROTATE(a,ip,j,iq,j) } for (j=1;j<=n;j++) { ROTATE(v,j,ip,j,iq) } ++(*nrot); } } } for (ip=1;ip<=n;ip++) { b[ip] += z[ip]; d[ip]=b[ip]; z[ip]=0.0; } } nrerror("Too many iterations in routine jacobi"); } #undef ROTATE #undef NRANSI /* (C) Copr. 1986-92 Numerical Recipes Software ?421.1-9. */