void
mmul(double *c,double *a,double *b,int n)
{
double *p,*q,s;
int i,j,k;
trnm(b,n);
for(i=0; i<n ; ++i,a+=n) {
for(j=0,q=b; j<n ; ++j) {
for(k=0,p=a,s=0.; k<n ; ++k) s+= *p++ * *q++;
*c++ =s;
}
}
trnm(b,n);
}
static void do_stuff(void)
{
//int m = 7;
int m = 3;
int n = 3;
double a[n*m], d[n], u[m*m], v[n*n], dmat[n*m];
// build and print a matrix of random numbers
FORI(n*m) a[i] = randombounds(10, 99);
PMATRIX(a, m, n);
// compute the SVD
int r = svd(d, a, u, m, v, n);
// show the results
FORI(n*m) dmat[i] = 0;
FORI(n) dmat[n*i+i] = d[i];
PMATRIX(dmat, m, n);
PMATRIX(u, m, m);
PMATRIX(v, n, n);
// check the reconstruction
double ud[m*n], udv[m*n];
rmmult(ud, u, dmat, m, m, n);
trnm(v,n);
rmmult(udv, ud, v, m, n, n);
PMATRIX(udv, m, n);
}
void
eigen(double *a,double *ev,int n)
{
double *dp;
dp=(double *)calloc(n,sizeof(double));
housev(a,ev,dp,n);
qrevec(ev,a,dp,n);
trnm(a,n);
free(dp);
}
