/* 1 0 pseudo-random normal (Gaussian) -6.0 <= nrand() < 6.0
*/
double nf_nrand(const Node *n, const Cell *c)
{
  int i;
  double r = -6;

  for( i = 0; i < 12; ++i)
    r += rand()/(RAND_MAX+1.0);

  return r;
}