From bb3808bb989db7e81755f1bfc7c6863d7c960e06 Mon Sep 17 00:00:00 2001
From: Richard Kreckel <Richard.Kreckel@uni-mainz.de>
Date: Fri, 25 Jan 2002 00:03:44 +0000
Subject: [PATCH] * mul::expand(): Considerable speedup through caching in
 nested loop.

---
 ginac/mul.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/ginac/mul.cpp b/ginac/mul.cpp
index 81d648a5..c7fb32a1 100644
--- a/ginac/mul.cpp
+++ b/ginac/mul.cpp
@@ -693,9 +693,10 @@ ex mul::expand(unsigned options) const
 				exvector distrseq;
 				distrseq.reserve(n1*n2);
 				for (int i1=0; i1<n1; ++i1) {
-					for (int i2=0; i2<n2; ++i2) {
-						distrseq.push_back(add1.op(i1) * add2.op(i2));
-					}
+					// cache the first operand (for efficiency):
+					const ex op1 = add1.op(i1);
+					for (int i2=0; i2<n2; ++i2)
+						distrseq.push_back(op1 * add2.op(i2));
 				}
 				last_expanded = (new add(distrseq))->
 				                 setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0));
-- 
2.50.0