From: Christian Bauer <Christian.Bauer@uni-mainz.de>
Date: Mon, 4 Mar 2002 20:01:00 +0000 (+0000)
Subject: * Sync 1.1 branch to 1.0 mainline.
X-Git-Tag: release_1-1-0~125
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=ef635afd43c75b9221abf9335736a459a590710e;p=ginac.git

* Sync 1.1 branch to 1.0 mainline.
---

diff --git a/NEWS b/NEWS
index 42f7a599..81208447 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,7 @@
 This file records noteworthy changes.
 
 1.1.0 (<date>)
+* "(x+1).subs(x==x-1)" now returns the correct result "x" instead of "x-1".
 
 1.0.5 (<date>)
 * (l)degree(s), coeff(s, n) and collect(s) were extended to accept expressions
diff --git a/check/exam_misc.cpp b/check/exam_misc.cpp
index 5613b375..849dc5ad 100644
--- a/check/exam_misc.cpp
+++ b/check/exam_misc.cpp
@@ -199,6 +199,33 @@ static unsigned exam_operator_semantics(void)
 	return result;
 }
 
+/* This checks whether subs() works as intended in some special cases. */
+static unsigned exam_subs(void)
+{
+	unsigned result = 0;
+	symbol x("x");
+	ex e1, e2;
+
+	// This used to fail in GiNaC 1.0.5 because it first substituted
+	// x+1 -> (x-1)+1 -> x, and then substituted again x -> x-1, giving
+	// the wrong result
+	e1 = x+1;
+	e2 = e1.subs(x == x-1);
+	if (!e2.is_equal(x)) {
+		clog << "(x+1).subs(x==x-1) erroneously returned " << e2 << " instead of x" << endl;
+		++result;
+	}
+
+	e1 = sin(1+sin(x));
+	e2 = e1.subs(sin(wild()) == cos(wild()));
+	if (!e2.is_equal(cos(1+cos(x)))) {
+		clog << "sin(1+sin(x)).subs(sin($1)==cos($1)) erroneously returned " << e2 << " instead of cos(1+cos(x))" << endl;
+		++result;
+	}
+
+	return result;
+}
+
 unsigned exam_misc(void)
 {
 	unsigned result = 0;
@@ -211,6 +238,7 @@ unsigned exam_misc(void)
 	result += exam_expand_power(); cout << '.' << flush;
 	result += exam_sqrfree(); cout << '.' << flush;
 	result += exam_operator_semantics(); cout << '.' << flush;
+	result += exam_subs(); cout << '.' << flush;
 	
 	if (!result) {
 		cout << " passed " << endl;
diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi
index dcee9335..717d5b10 100644
--- a/doc/tutorial/ginac.texi
+++ b/doc/tutorial/ginac.texi
@@ -3191,11 +3191,11 @@ Some examples:
 b^3+a^3+(x+y)^3
 > subs(a^4+b^4+(x+y)^4,$1^2==$1^3);
 b^4+a^4+(x+y)^4
-> subs((a+b+c)^2,a+b=x);
+> subs((a+b+c)^2,a+b==x);
 (a+b+c)^2
 > subs((a+b+c)^2,a+b+$1==x+$1);
 (x+c)^2
-> subs(a+2*b,a+b=x);
+> subs(a+2*b,a+b==x);
 a+2*b
 > subs(4*x^3-2*x^2+5*x-1,x==a);
 -1+5*a-2*a^2+4*a^3
diff --git a/ginac/expairseq.cpp b/ginac/expairseq.cpp
index c18fadec..36261a98 100644
--- a/ginac/expairseq.cpp
+++ b/ginac/expairseq.cpp
@@ -402,7 +402,7 @@ ex expairseq::subs(const lst &ls, const lst &lr, bool no_pattern) const
 {
 	epvector *vp = subschildren(ls, lr, no_pattern);
 	if (vp)
-		return ex_to<basic>(thisexpairseq(vp, overall_coeff)).basic::subs(ls, lr, no_pattern);
+		return ex_to<basic>(thisexpairseq(vp, overall_coeff));
 	else
 		return basic::subs(ls, lr, no_pattern);
 }