Hello. LGTM.
Thanks, Gilles P.S. Thinking of releasing 1.3? Le lun. 10 juin 2019 à 14:55, Alex Herbert <alex.d.herb...@gmail.com> a écrit : > > I've submitted a PR with the functionality discussed in this thread for > JumpableUniformRandomProvider [1]. > > Some notes: > > - The jump must return a copy. > > This requires a bit of code all the way up to the base implementations > of IntProvider and LongProvider to copy the current state. I've done > this explicitly with copy constructors to avoid using clone() [2]. > > > - The jump has a few requirements that are tested: > > 1. The copy is a new instance of the same class. > > 2. The sequence output from the original RNG after the jump must match > the reference implementation output. > > 3. The sequence output from the copy must match what would have been > output from the original RNG. > > > - The default implementations of the providers have cached state > > To ensure the state is copied this is tested by comparing the state of > the copy with the state of the original pre-jump. This does not require > any knowledge of the original state. Just that the state can be accesses > using RestorableUniformRandomProvider. > > To ensure that the state is cleared in the original RNG post-jump > requires that the state pre-jump is not zero and the state after the > jump is zero. > > One method is to: create a generator, call nextInt or nextBoolean to > make it cache some state, do the jump; compare the output of nextInt or > nextBoolean to the copy and test it is different. However this requires > that the initial state is new (all zero bytes) and so the test must be > called in every test class for each generator by passing a new instance. > > Alternatively a test is made using the state from > RestorableUniformRandomProvider. The size of the default state is known > and post-jump is checked to ensure it is zero. This test does not > require the pre-jump state to be zero and thus can be put into a > parametric test for all the JumpableUniformRandomProviders. > > So the tests to check the output sequence post-jump are in the > individual tests for each provider and a JumpableProvidersParametricTest > tests the general requirements of a Jumpable RNG. This ensures all > generators in the library pass tests to ensure common functionality (the > copy is a new instance, the state is the same as the original, the > post-jump state of the original has reset the cached state). > > > - Some providers are LongJumpable > > This will be added for RNG-98 and I created this PR with future > functionality in mind. The jump function to advance the state is named > performJump. For those without a LongJump the coefficients are not > passed as a parameter and can be hard coded. For any generator with a > LongJump function the computation of the jump in the performJump > function accepts an array of coefficients. This will be called with the > appropriate long jump coefficients to implement LongJumpable. The rest > of the code will be unchanged and new tests can be added to check the > long jump. > > > Comments are welcomed. > > Alex > > > [1] https://github.com/apache/commons-rng/pull/48 > > [2] https://www.artima.com/intv/bloch13.html > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
