From a017d011247b28bd4d3fd7d797144a543a1440b6 Mon Sep 17 00:00:00 2001
From: Sven Verdoolaege <skimo@kotnet.org>
Date: Mon, 31 Mar 2008 16:33:44 +0200
Subject: [PATCH] euler.cc: evalue_derive: handle constant polynomials

Usually, polynomials with only a constant term are reduced
to that constant.  However, the input evalue may contain
such polynomials (possibly read from the input) and so
we have to deal with them.
---
 euler.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/euler.cc b/euler.cc
index e25465e..b56d203 100644
--- a/euler.cc
+++ b/euler.cc
@@ -363,9 +363,14 @@ static void evalue_derive(evalue *poly, int var)
 	return;
     }
 
-    assert(poly->x.p->size > 1);
+    assert(poly->x.p->size >= 1);
     enode *p = poly->x.p;
     free_evalue_refs(&p->arr[0]);
+    if (p->size == 1) {
+	free(p);
+	evalue_set_si(poly, 0, 1);
+	return;
+    }
     if (p->size == 2) {
 	value_clear(poly->d);
 	*poly = p->arr[1];
-- 
2.11.4.GIT