From: Richard Kreckel <Richard.Kreckel@uni-mainz.de>
Date: Fri, 17 Oct 2003 14:26:09 +0000 (+0000)
Subject: * Sync to HEAD.
X-Git-Tag: release_1-1-4~2
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=34d0e5a60a8255b6f6273b6627b4d7b6df953885;p=ginac.git

* Sync to HEAD.
---

diff --git a/check/times.cpp b/check/times.cpp
index 9ada2bf6..ce5730b9 100644
--- a/check/times.cpp
+++ b/check/times.cpp
@@ -23,8 +23,35 @@
 #include <stdexcept>
 #include "times.h"
 
+/** Generate a random amount of symbols and destroy them again immediatly.
+ *  This operation effectively makes the serial numbers of all subsequent
+ *  symbols unpredictable.  If the serials are unpredictable, then so are
+ *  their hash values.  If the hash values are unpredictable, then so are
+ *  the canonical orderings.  If the canonical orderings are unpredictable,
+ *  all subsequent times are subject to some variation.  This variation,
+ *  however is natural and desireable for two reasons: First, we cannot know
+ *  how many symbols have been generated before in real world computations.
+ *  Second, the following timings are subject to some semi-random variation
+ *  anyways because short timings need to be repeated until enough time has
+ *  gone by for the measurement to be reliable.  During this process the serial
+ *  numbers will be shifted anyways in a semi-random way.  It is better not
+ *  to lull the user in a false sense of reproducibility and instead confront
+ *  her with the normal variation to be expected.
+ */
+void randomify_symbol_serials()
+{
+	srand((unsigned)time(NULL));
+	const int m = rand() % 666;
+	for (int s=0; s<m; ++s ) {
+		symbol* tmp = new symbol;
+		delete tmp;
+	}
+}
+
 int main()
 {
+	randomify_symbol_serials();
+
 	unsigned result = 0;
 	
 #define TIME(which) \