check: indicate the test failures with non-zero exit code; split test programs.

[ginac.git] / check / randomize_serials.cpp

diff --git a/check/randomize_serials.cpp b/check/randomize_serials.cpp
new file mode 100644 (file)
index 0000000..ad29a1b
--- /dev/null
+++ b/check/randomize_serials.cpp
@@ -0,0 +1,31 @@
+#include <cstdlib>
+#include <ctime>
+#include "ginac.h"
+using namespace std;
+using namespace GiNaC;
+
+/** 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(time(NULL));
+       const int m = rand() % 666;
+       for (int s=0; s<m; ++s ) {
+               symbol("dummy");
+       }
+}
+
+