add isl_qpolynomial_coeff

diff --git a/isl_polynomial.c b/isl_polynomial.c
index d501f65..259ed32 100644 (file)
--- a/isl_polynomial.c
+++ b/isl_polynomial.c
@@ -2512,6 +2512,86 @@ int isl_qpolynomial_degree(__isl_keep isl_qpolynomial *poly)
        return isl_upoly_degree(poly->upoly, ovar, ovar + nvar);
 }
 
+__isl_give struct isl_upoly *isl_upoly_coeff(__isl_keep struct isl_upoly *up,
+       unsigned pos, int deg)
+{
+       int i;
+       struct isl_upoly_rec *rec;
+
+       if (!up)
+               return NULL;
+
+       if (isl_upoly_is_cst(up) || up->var < pos) {
+               if (deg == 0)
+                       return isl_upoly_copy(up);
+               else
+                       return isl_upoly_zero(up->ctx);
+       }
+
+       rec = isl_upoly_as_rec(up);
+       if (!rec)
+               return NULL;
+
+       if (up->var == pos) {
+               if (deg < rec->n)
+                       return isl_upoly_copy(rec->p[deg]);
+               else
+                       return isl_upoly_zero(up->ctx);
+       }
+
+       up = isl_upoly_copy(up);
+       up = isl_upoly_cow(up);
+       rec = isl_upoly_as_rec(up);
+       if (!rec)
+               goto error;
+
+       for (i = 0; i < rec->n; ++i) {
+               struct isl_upoly *t;
+               t = isl_upoly_coeff(rec->p[i], pos, deg);
+               if (!t)
+                       goto error;
+               isl_upoly_free(rec->p[i]);
+               rec->p[i] = t;
+       }
+
+       return up;
+error:
+       isl_upoly_free(up);
+       return NULL;
+}
+
+/* Return coefficient of power "deg" of variable "t_pos" of type "type".
+ */
+__isl_give isl_qpolynomial *isl_qpolynomial_coeff(
+       __isl_keep isl_qpolynomial *qp,
+       enum isl_dim_type type, unsigned t_pos, int deg)
+{
+       unsigned g_pos;
+       struct isl_upoly *up;
+       isl_qpolynomial *c;
+
+       if (!qp)
+               return NULL;
+
+       isl_assert(qp->div->ctx, t_pos < isl_dim_size(qp->dim, type),
+                       return NULL);
+
+       g_pos = pos(qp->dim, type) + t_pos;
+       up = isl_upoly_coeff(qp->upoly, g_pos, deg);
+
+       c = isl_qpolynomial_alloc(isl_dim_copy(qp->dim), qp->div->n_row, up);
+       if (!c)
+               return NULL;
+       isl_mat_free(c->div);
+       c->div = isl_mat_copy(qp->div);
+       if (!c->div)
+               goto error;
+       return c;
+error:
+       isl_qpolynomial_free(c);
+       return NULL;
+}
+
 /* 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.

diff --git a/isl_polynomial_private.h b/isl_polynomial_private.h
index 3fb88f1..58c2766 100644 (file)
--- a/isl_polynomial_private.h
+++ b/isl_polynomial_private.h
@@ -132,6 +132,9 @@ __isl_give isl_qpolynomial *isl_qpolynomial_min_cst(
        __isl_take isl_qpolynomial *qp1, __isl_take isl_qpolynomial *qp2);
 
 int isl_qpolynomial_degree(__isl_keep isl_qpolynomial *poly);
+__isl_give isl_qpolynomial *isl_qpolynomial_coeff(
+       __isl_keep isl_qpolynomial *poly,
+       enum isl_dim_type type, unsigned pos, int deg);
 
 __isl_give isl_vec *isl_qpolynomial_extract_affine(
        __isl_keep isl_qpolynomial *qp);