From: Chris Dams <Chris.Dams@mi.infn.it>
Date: Tue, 14 Mar 2006 18:54:55 +0000 (+0000)
Subject: Vlamirs patch for automatically simplifying e.g., csgn(x)^3 -> csgn(x).
X-Git-Tag: release_1-4-0~102
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=ae7c2d39ba090f4425995d0d1eb9fff1c91a9489;p=ginac.git

Vlamirs patch for automatically simplifying e.g., csgn(x)^3 -> csgn(x).
---

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index 47252a8f..a8f82d8e 100644
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -252,10 +252,23 @@ static ex csgn_conjugate(const ex& arg)
 	return csgn(arg);
 }
 
+static ex csgn_power(const ex & arg, const ex & exp)
+{
+	if (is_a<numeric>(exp) && exp.info(info_flags::positive) && ex_to<numeric>(exp).is_integer()) {
+		if (ex_to<numeric>(exp).is_odd())
+			return csgn(arg);
+		else
+			return power(csgn(arg), _ex2).hold();
+	} else
+		return power(csgn(arg), exp).hold();
+}
+
+
 REGISTER_FUNCTION(csgn, eval_func(csgn_eval).
                         evalf_func(csgn_evalf).
                         series_func(csgn_series).
-                        conjugate_func(csgn_conjugate));
+                        conjugate_func(csgn_conjugate).
+                        power_func(csgn_power));
 
 
 //////////