From: Jens Vollinga <jensv@nikhef.nl>
Date: Fri, 20 May 2011 11:55:35 +0000 (+0200)
Subject: Fixed a bug in is_polynomial() that caused expressions like
X-Git-Tag: release_1-6-0~9
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=293ff6f6fe89c3e5413c8da57feedf3bd2016cd7

Fixed a bug in is_polynomial() that caused expressions like
sqrt(x*x+1)*sqrt(x+1) to be wrongly identified as polynomials in x.
Thanks to Florent Hivert for reporting.
---

diff --git a/check/exam_paranoia.cpp b/check/exam_paranoia.cpp
index 5fdfb350..972270f8 100644
--- a/check/exam_paranoia.cpp
+++ b/check/exam_paranoia.cpp
@@ -494,6 +494,18 @@ static unsigned exam_paranoia19()
 	return 0;
 }
 
+// Bug in expairseq::is_polynomial (fixed 2011-05-20).
+static unsigned exam_paranoia20()
+{
+	symbol x("x");
+	ex e = sqrt(x*x+1)*sqrt(x+1);
+	if (e.is_polynomial(x)) {
+		clog << "sqrt(x*x+1)*sqrt(x+1) is wrongly reported to be a polynomial in x\n";
+		return 1;
+	}
+	return 0;
+}
+
 unsigned exam_paranoia()
 {
 	unsigned result = 0;
@@ -519,6 +531,7 @@ unsigned exam_paranoia()
 	result += exam_paranoia17();  cout << '.' << flush;
 	result += exam_paranoia18();  cout << '.' << flush;
 	result += exam_paranoia19();  cout << '.' << flush;
+	result += exam_paranoia20();  cout << '.' << flush;
 	
 	return result;
 }
diff --git a/ginac/expairseq.cpp b/ginac/expairseq.cpp
index 90ec7635..88d986ea 100644
--- a/ginac/expairseq.cpp
+++ b/ginac/expairseq.cpp
@@ -377,11 +377,22 @@ ex expairseq::conjugate() const
 
 bool expairseq::is_polynomial(const ex & var) const
 {
-	if (!is_exactly_a<add>(*this) && !is_exactly_a<mul>(*this))
+	if (is_exactly_a<add>(*this)) {
+		for (epvector::const_iterator i=seq.begin(); i!=seq.end(); ++i) {
+			if (!(i->rest).is_polynomial(var)) {
+				return false;
+			}
+		}
+	}
+	else if (is_exactly_a<mul>(*this)) {
+		for (epvector::const_iterator i=seq.begin(); i!=seq.end(); ++i) {
+			if (!(i->rest).is_polynomial(var) || !(i->coeff.info(info_flags::integer))) {
+				return false;
+			}
+		}
+	}
+	else {
 		return basic::is_polynomial(var);
-	for (epvector::const_iterator i=seq.begin(); i!=seq.end(); ++i) {
-		if (!(i->rest).is_polynomial(var))
-			return false;
 	}
 	return true;
 }