From: Vladimir V. Kisil <kisilv@maths.leeds.ac.uk>
Date: Sat, 28 Dec 2013 23:58:40 +0000 (+0000)
Subject: Fix evaluation of log(p^a) -> a*log(p), if p>0 and a is real.
X-Git-Tag: release_1-6-3~30
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=98433210d31a34b55c8283eb7fb7767d6c830e14

Fix evaluation of log(p^a) -> a*log(p), if p>0 and a is real.

This evaluation was broken with commit e5c76f659e2e882d.
---

diff --git a/ginac/inifcns_trans.cpp b/ginac/inifcns_trans.cpp
index 6ee0a23b..56d909c6 100644
--- a/ginac/inifcns_trans.cpp
+++ b/ginac/inifcns_trans.cpp
@@ -174,7 +174,12 @@ static ex log_eval(const ex & x)
 		if (t.info(info_flags::real))
 			return t;
 	}
-	
+
+	// log(p^a) -> a*log(p), if p>0 and a is real
+	if (is_exactly_a<power>(x) && x.op(0).info(info_flags::positive) && x.op(1).info(info_flags::real)) {
+		return x.op(1)*log(x.op(0));
+	}
+
 	return log(x).hold();
 }