From: Alexei Sheplyakov <Alexei.Sheplyakov@gmail.com>
Date: Sun, 13 Oct 2013 10:16:16 +0000 (+0300)
Subject: mul::info(): cache the result of the positiveness/negativeness checks, ...
X-Git-Tag: release_1-6-3~42
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=31fef4a6bc14afa46a297b3b87f94204d6c726d5

mul::info(): cache the result of the positiveness/negativeness checks, ...

... and use the cached result if possible.
---

diff --git a/check/CMakeLists.txt b/check/CMakeLists.txt
index 0445a4a1..42fe50e1 100644
--- a/check/CMakeLists.txt
+++ b/check/CMakeLists.txt
@@ -6,6 +6,7 @@ set(ginac_tests
 	check_inifcns
 	check_matrices
 	check_lsolve
+	check_mul_info
 	heur_gcd_bug
 	exam_paranoia
 	exam_heur_gcd
diff --git a/check/check_mul_info.cpp b/check/check_mul_info.cpp
new file mode 100644
index 00000000..34652f8d
--- /dev/null
+++ b/check/check_mul_info.cpp
@@ -0,0 +1,14 @@
+#include "ginac.h"
+#include <iostream>
+using namespace GiNaC;
+
+int main(int argc, char** argv)
+{
+	symbol x("x"), y("y");
+	ex e = x*y;
+	if (!e.info(info_flags::indefinite)) {
+		std::cerr << "eek, product of two symbols is NOT indefinite";
+		return 1;
+	}
+	return 0;
+}
diff --git a/ginac/mul.cpp b/ginac/mul.cpp
index cee5cd7a..64660a28 100644
--- a/ginac/mul.cpp
+++ b/ginac/mul.cpp
@@ -307,6 +307,13 @@ bool mul::info(unsigned inf) const
 		}
 		case info_flags::positive:
 		case info_flags::negative: {
+			if ((inf==info_flags::positive) && (flags & status_flags::is_positive))
+				return true;
+			else if ((inf==info_flags::negative) && (flags & status_flags::is_negative))
+				return true;
+			if (flags & status_flags::purely_indefinite)
+				return false;
+
 			bool pos = true;
 			epvector::const_iterator i = seq.begin(), end = seq.end();
 			while (i != end) {
@@ -320,9 +327,12 @@ bool mul::info(unsigned inf) const
 			}
 			if (overall_coeff.info(info_flags::negative))
 				pos = !pos;
-			return (inf ==info_flags::positive? pos : !pos);
+			setflag(pos ? status_flags::is_positive : status_flags::is_negative);
+			return (inf == info_flags::positive? pos : !pos);
 		}
 		case info_flags::nonnegative: {
+			if  (flags & status_flags::is_positive)
+				return true;
 			bool pos = true;
 			epvector::const_iterator i = seq.begin(), end = seq.end();
 			while (i != end) {
@@ -373,6 +383,21 @@ bool mul::info(unsigned inf) const
 				return false;
 			return pos; 
 		}
+		case info_flags::indefinite: {
+			if (flags & status_flags::purely_indefinite)
+				return true;
+			if (flags & (status_flags::is_positive | status_flags::is_negative))
+				return false;
+			epvector::const_iterator i = seq.begin(), end = seq.end();
+			while (i != end) {
+				const ex& term = recombine_pair_to_ex(*i);
+				if (term.info(info_flags::positive) || term.info(info_flags::negative))
+					return false;
+				++i;
+			}
+			setflag(status_flags::purely_indefinite);
+			return true;
+		}
 	}
 	return inherited::info(inf);
 }