[Octave-bug-tracker] [bug #53299] Several rand/randn bugs with state/seed behavior.

[Rik]

Follow-up Comment #19, bug #53299 (project octave):

@Mike: For conv2 bugs, see bug #39314 and bug #34893.  This function has
consistently been a problem.  The root issue now seems to be that the inner
and outer convolutions are performed in different directions and the summation
of floating point numbers can accumulate different small errors because of
that.

For some reason, the random numbers that are generated by the "seed" generator
are apparently precisely represented in IEEE-854 so that they do not
accumulate these errors.  I tested with different random values of the seed
itself and the conv2 test always pass.  Thus, it is not the particular value
(42) that we use in the BIST tests, but the fact that we use the "seed"
generator.

I also generated a random set of numbers, saved them to a file, and then
re-started Octave.  I wanted to make sure that it wasn't a strange side effect
like initializing the "seed" generator which also set some CPU processor
flags.  But reading in the numbers and executing the conv2 test on them works.
 Hence, it really is the numbers themselves that have the necessary magic.

Anyways, it would be better to resolve the issue with the conv2 algorithm
rather than messing with our random number generation.

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