Be more careful about final top-level substitution.

[ginac.git] / check / exam_misc.cpp

diff --git a/check/exam_misc.cpp b/check/exam_misc.cpp
index 9dbfd6bc41d71850566681b337c004d3fea647cc..fc9c41ebc48e61d302f544fce1fb04bf662f7220 100644 (file)
--- a/check/exam_misc.cpp
+++ b/check/exam_misc.cpp
@@ -219,6 +219,15 @@ static unsigned exam_subs()
                ++result;
        }
 
+       // And this used to fail in GiNaC 1.5.8 because it first substituted
+       // exp(x) -> exp(log(x)) -> x, and then substitued again x -> log(x)
+       e1 = exp(x);
+       e2 = e1.subs(x == log(x));
+       if (!e2.is_equal(x)) {
+               clog << "exp(x).subs(x==log(x)) 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)))) {