From: Vladimir V. Kisil <kisilv@maths.leeds.ac.uk>
Date: Mon, 11 Sep 2017 21:12:36 +0000 (+0200)
Subject: [PATCH] Fix bug in evaluation of real and imaginary parts of powers.
X-Git-Tag: release_1-7-3~18
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=ac58816ee70e2f9e8d863f3869ce512a4009ddc9;p=ginac.git

[PATCH] Fix bug in evaluation of real and imaginary parts of powers.

Be more careful when simplifying Re(a^c) -> a^c and Im(a^c) -> 0.

Thanks to Jan Rheinländer for reporting this.
---

diff --git a/ginac/power.cpp b/ginac/power.cpp
index 26194928..a45e1fa3 100644
--- a/ginac/power.cpp
+++ b/ginac/power.cpp
@@ -669,7 +669,8 @@ ex power::real_part() const
 	// basis == a+I*b, exponent == c+I*d
 	const ex a = basis.real_part();
 	const ex c = exponent.real_part();
-	if (basis.is_equal(a) && exponent.is_equal(c)) {
+	if (basis.is_equal(a) && exponent.is_equal(c) &&
+	    (a.info(info_flags::nonnegative) || c.info(info_flags::integer))) {
 		// Re(a^c)
 		return *this;
 	}
@@ -704,7 +705,8 @@ ex power::imag_part() const
 	// basis == a+I*b, exponent == c+I*d
 	const ex a = basis.real_part();
 	const ex c = exponent.real_part();
-	if (basis.is_equal(a) && exponent.is_equal(c)) {
+	if (basis.is_equal(a) && exponent.is_equal(c) &&
+	    (a.info(info_flags::nonnegative) || c.info(info_flags::integer))) {
 		// Im(a^c)
 		return 0;
 	}