From 56bbb99adc43dad22ee615380d4446a87b713cb8 Mon Sep 17 00:00:00 2001
From: Jens Vollinga <jensv@nikhef.nl>
Date: Sat, 21 May 2011 01:30:08 +0200
Subject: [PATCH] Limiting the costly symmetrization tests inside
 simplify_indexed() to cases where at least one antisymmetric or cyclic
 non-free index is involved. Thanks to P.G.Clark for reporting the problem.

---
 ginac/indexed.cpp  | 37 +++++++++++++++++++++++--------------
 ginac/symmetry.cpp | 12 ++++++++++++
 ginac/symmetry.h   |  2 ++
 3 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/ginac/indexed.cpp b/ginac/indexed.cpp
index b59240e0..b85c3869 100644
--- a/ginac/indexed.cpp
+++ b/ginac/indexed.cpp
@@ -797,6 +797,7 @@ ex simplify_indexed_product(const ex & e, exvector & free_indices, exvector & du
 
 	// Perform contractions
 	bool something_changed = false;
+	bool has_nonsymmetric = false;
 	GINAC_ASSERT(v.size() > 1);
 	exvector::iterator it1, itend = v.end(), next_to_last = itend - 1;
 	for (it1 = v.begin(); it1 != next_to_last; it1++) {
@@ -806,6 +807,7 @@ try_again:
 			continue;
 
 		bool first_noncommutative = (it1->return_type() != return_types::commutative);
+		bool first_nonsymmetric = ex_to<symmetry>(ex_to<indexed>(*it1).get_symmetry()).has_nonsymmetric();
 
 		// Indexed factor found, get free indices and look for contraction
 		// candidates
@@ -882,6 +884,11 @@ contraction_done:
 				something_changed = true;
 				goto try_again;
 			}
+			else if (!has_nonsymmetric &&
+					(first_nonsymmetric ||
+					 ex_to<symmetry>(ex_to<indexed>(*it2).get_symmetry()).has_nonsymmetric())) {
+				has_nonsymmetric = true;
+			}
 		}
 	}
 
@@ -935,20 +942,22 @@ contraction_done:
 	// The result should be symmetric with respect to exchange of dummy
 	// indices, so if the symmetrization vanishes, the whole expression is
 	// zero. This detects things like eps.i.j.k * p.j * p.k = 0.
-	ex q = idx_symmetrization<idx>(r, local_dummy_indices);
-	if (q.is_zero()) {
-		free_indices.clear();
-		return _ex0;
-	}
-	q = idx_symmetrization<varidx>(q, local_dummy_indices);
-	if (q.is_zero()) {
-		free_indices.clear();
-		return _ex0;
-	}
-	q = idx_symmetrization<spinidx>(q, local_dummy_indices);
-	if (q.is_zero()) {
-		free_indices.clear();
-		return _ex0;
+	if (has_nonsymmetric) {
+		ex q = idx_symmetrization<idx>(r, local_dummy_indices);
+		if (q.is_zero()) {
+			free_indices.clear();
+			return _ex0;
+		}
+		q = idx_symmetrization<varidx>(q, local_dummy_indices);
+		if (q.is_zero()) {
+			free_indices.clear();
+			return _ex0;
+		}
+		q = idx_symmetrization<spinidx>(q, local_dummy_indices);
+		if (q.is_zero()) {
+			free_indices.clear();
+			return _ex0;
+		}
 	}
 
 	// Dummy index renaming
diff --git a/ginac/symmetry.cpp b/ginac/symmetry.cpp
index d93e34cb..a44cfcc5 100644
--- a/ginac/symmetry.cpp
+++ b/ginac/symmetry.cpp
@@ -270,6 +270,18 @@ void symmetry::do_print_tree(const print_tree & c, unsigned level) const
 // non-virtual functions in this class
 //////////
 
+bool symmetry::has_nonsymmetric() const
+{
+	if (type == antisymmetric || type == cyclic)
+		return true;
+
+	for (exvector::const_iterator i=children.begin(); i!=children.end(); ++i)
+		if (ex_to<symmetry>(*i).has_nonsymmetric())
+			return true;
+
+	return false;
+}
+
 bool symmetry::has_cyclic() const
 {
 	if (type == cyclic)
diff --git a/ginac/symmetry.h b/ginac/symmetry.h
index 54a2cb82..fa897be9 100644
--- a/ginac/symmetry.h
+++ b/ginac/symmetry.h
@@ -80,6 +80,8 @@ public:
 
 	/** Check whether this node actually represents any kind of symmetry. */
 	bool has_symmetry() const {return type != none || !children.empty(); }
+	/** Check whether this node involves anything non symmetric. */
+	bool has_nonsymmetric() const;
 	/** Check whether this node involves a cyclic symmetry. */
 	bool has_cyclic() const;
 
-- 
2.44.0