add isl_qpolynomial_homogenize

diff --git a/include/isl_polynomial.h b/include/isl_polynomial.h
index 0813b75..d097fcf 100644 (file)
--- a/include/isl_polynomial.h
+++ b/include/isl_polynomial.h
@@ -69,6 +69,9 @@ int isl_qpolynomial_as_polynomial_on_domain(__isl_keep isl_qpolynomial *qp,
        int (*fn)(__isl_take isl_basic_set *bset,
                  __isl_take isl_qpolynomial *poly, void *user), void *user);
 
+__isl_give isl_qpolynomial *isl_qpolynomial_homogenize(
+       __isl_take isl_qpolynomial *poly);
+
 struct isl_term;
 typedef struct isl_term isl_term;
 

diff --git a/isl_polynomial.c b/isl_polynomial.c
index 3f6785c..ec5dde5 100644 (file)
--- a/isl_polynomial.c
+++ b/isl_polynomial.c
@@ -2499,6 +2499,87 @@ int isl_qpolynomial_degree(__isl_keep isl_qpolynomial *poly)
        return isl_upoly_degree(poly->upoly, ovar, ovar + nvar);
 }
 
+/* Homogenize the polynomial in the variables first (inclusive) up to
+ * last (exclusive) by inserting powers of variable first.
+ * Variable first is assumed not to appear in the input.
+ */
+__isl_give struct isl_upoly *isl_upoly_homogenize(
+       __isl_take struct isl_upoly *up, int deg, int target,
+       int first, int last)
+{
+       int i;
+       struct isl_upoly_rec *rec;
+
+       if (!up)
+               return NULL;
+       if (isl_upoly_is_zero(up))
+               return up;
+       if (deg == target)
+               return up;
+       if (isl_upoly_is_cst(up) || up->var < first) {
+               struct isl_upoly *hom;
+
+               hom = isl_upoly_pow(up->ctx, first, target - deg);
+               if (!hom)
+                       goto error;
+               rec = isl_upoly_as_rec(hom);
+               rec->p[target - deg] = isl_upoly_mul(rec->p[target - deg], up);
+
+               return hom;
+       }
+
+       up = isl_upoly_cow(up);
+       rec = isl_upoly_as_rec(up);
+       if (!rec)
+               goto error;
+
+       for (i = 0; i < rec->n; ++i) {
+               if (isl_upoly_is_zero(rec->p[i]))
+                       continue;
+               rec->p[i] = isl_upoly_homogenize(rec->p[i],
+                               up->var < last ? deg + i : i, target,
+                               first, last);
+               if (!rec->p[i])
+                       goto error;
+       }
+
+       return up;
+error:
+       isl_upoly_free(up);
+       return NULL;
+}
+
+/* Homogenize the polynomial in the set variables by introducing
+ * powers of an extra set variable at position 0.
+ */
+__isl_give isl_qpolynomial *isl_qpolynomial_homogenize(
+       __isl_take isl_qpolynomial *poly)
+{
+       unsigned ovar;
+       unsigned nvar;
+       int deg = isl_qpolynomial_degree(poly);
+
+       if (deg < -1)
+               goto error;
+
+       poly = isl_qpolynomial_insert_dims(poly, isl_dim_set, 0, 1);
+       poly = isl_qpolynomial_cow(poly);
+       if (!poly)
+               goto error;
+
+       ovar = isl_dim_offset(poly->dim, isl_dim_set);
+       nvar = isl_dim_size(poly->dim, isl_dim_set);
+       poly->upoly = isl_upoly_homogenize(poly->upoly, 0, deg,
+                                               ovar, ovar + nvar);
+       if (!poly->upoly)
+               goto error;
+
+       return poly;
+error:
+       isl_qpolynomial_free(poly);
+       return NULL;
+}
+
 __isl_give isl_term *isl_term_alloc(__isl_take isl_dim *dim,
        __isl_take isl_mat *div)
 {