#ifndef rdo_linear_algebra_H
#define rdo_linear_algebra_H
/* Some linear algebra operations. */

#define rdo_linear_algebra_H_COPYRIGHT "Copyright © 2008 Danillo Pereira and J. Stolfi, UNICAMP"
/* Last edited on 2009-02-10 15:34:08 by stolfi */

#include <dspmat.h>

#define TINY_SUM 1e-200
  /* A tiny value used to initialize the sum of a set of values,
    instead of zero, in order to avoid division by zero when
    normalizing those values. Thus, if all un-normalized values are
    zero, the normalized ones will also be zero (rather than {NAN]s).
    On the other hand, if any value is significative (greater than
    {1e16*TINY_SUM}), this trick will not have any effect on the
    result. !!! Check whether the trick is really needed !!! */

void rdo_linalg_set_some_elements(double v[], int n, int sel[], double w[], int m);
  /* Sets all elements {v[0..n-1]} to zero, then sets {v[sel[j]]=w[j]},
    for each {j} in {0..m-1}. */

#endif