* Fixed bug in example

[ginac.git] / check / times.cpp

diff --git a/check/times.cpp b/check/times.cpp
index e405403e9a4afea2ff375d8254de2a8b30738a91..ce5730b9f5d7bf48707d849fb3ab6f9ab324a652 100644 (file)
--- 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) \
@@ -39,6 +66,7 @@ try { \
        TIME(gammaseries)
        TIME(vandermonde)
        TIME(toeplitz)
+       TIME(hashmap)
        TIME(lw_A)
        TIME(lw_B)
        TIME(lw_C)