*** UPDATE: added a 'Help!' button to explain about PRNGs... ------------------------------------------------------------------ Runs spectral and chi-squared tests on five pseudorandom number generators, including Scratch's built-in (probably OS-dependent), and one from the 1960's called "RANDU", which was very bad! -See https://en.wikipedia.org/wiki/RANDU to read all about that. My original seeded pseudorandom cycle project (below) used a simple formula to cycle through the values from -2147483645 to +2147483645 (except zero) in a well-defined order, but which *appeared* to be random. That sequence is retained within this project as "quick-cycle-1" (though it's much more efficient now). I've created another similar sequence which cycles through numbers from 1 to 4294967296(=2^32) in a random-looking order. This is called "quick-cycle-2" in here. *** It's worth noting that, since quick-cycle-2 is based on a power-of-two cycle, there are correlations in the low-order bits, which the chi-squared test can pick up with certain skips (e.g. try it with 2,2,2). I've brought these two together to make a *much* longer sequence, with a length of nearly 2^64 (>18 million million million). Because of floating-point rounding, this only returns integers in the range one to 500 billion (though there's a custom block to 'pick random' in a range, including as decimal values, for all three of the cycles). There are also blocks to extract the current seed info from the three cycles, so you can interrupt a cycle where it is, use it from a different seed, and then restart later on from the interrupted position.
