#include #include #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