evalR_Rfs()

static void evalR_Rfs ( double *  pts, unsigned  dim, double *  p, const double *  c, const double *  r  )

static

Evaluate the integration points for all 2^n points (+/-r,...+/-r)

A Gray-code ordering is used to minimize the number of coordinate updates in p, although this doesn't matter as much now that we are saving all pts.

{
     unsigned i;
     unsigned signs = 0; /* 0/1 bit = +/- for corresponding element of r[] */

     /* We start with the point where r is ADDed in every coordinate
        (this implies signs=0). */
     for (i = 0; i < dim; ++i)
          p[i] = c[i] + r[i];

     /* Loop through the points in Gray-code ordering */
     for (i = 0;; ++i) {
          unsigned mask, d;

          memcpy(pts, p, sizeof(double) * dim); pts += dim;

          d = ls0(i);   /* which coordinate to flip */
          if (d >= dim)
               break;

          /* flip the d-th bit and add/subtract r[d] */
          mask = 1U << d;
          signs ^= mask;
          p[d] = (signs & mask) ? c[d] - r[d] : c[d] + r[d];
     }
}