polysign_polylib.c

   1 #include <barvinok/util.h>
   2 #include <barvinok/options.h>
   3 #include "polysign.h"
   4
   5 static enum order_sign interval_minmax(Polyhedron *I)
   6 {
   7     int i;
   8     int min = 1;
   9     int max = -1;
  10     assert(I->Dimension == 1);
  11     POL_ENSURE_VERTICES(I);
  12     for (i = 0; i < I->NbRays; ++i) {
  13         if (value_pos_p(I->Ray[i][1]))
  14             max = 1;
  15         else if (value_neg_p(I->Ray[i][1]))
  16             min = -1;
  17         else {
  18             if (max < 0)
  19                 max = 0;
  20             if (min > 0)
  21                 min = 0;
  22         }
  23     }
  24     if (min > 0)
  25         return order_gt;
  26     if (max < 0)
  27         return order_lt;
  28     if (min == max)
  29         return order_eq;
  30     if (max == 0)
  31         return order_le;
  32     if (min == 0)
  33         return order_ge;
  34     return order_unknown;
  35 }
  36
  37 /* Returns the sign of the affine function specified by T on the polyhedron D */
  38 enum order_sign PL_polyhedron_affine_sign(Polyhedron *D, Matrix *T,
  39                                             struct barvinok_options *options)
  40 {
  41     enum order_sign sign;
  42     Polyhedron *I = Polyhedron_Image(D, T, options->MaxRays);
  43     if (POL_ISSET(options->MaxRays, POL_INTEGER))
  44         I = DomainConstraintSimplify(I, options->MaxRays);
  45     if (emptyQ2(I)) {
  46         Polyhedron_Free(I);
  47         I = Polyhedron_Image(D, T, options->MaxRays);
  48     }
  49     sign = interval_minmax(I);
  50     Polyhedron_Free(I);
  51     return sign;
  52 }