On Sun, May 1, 2011 at 7:43 AM, Ronan Lamy <[email protected]> wrote: > Le samedi 30 avril 2011 à 23:47 -0700, Ondrej Certik a écrit : >> On Sat, Apr 30, 2011 at 10:36 AM, Haz <[email protected]> wrote: >> > So a few things to respond to... >> > Tom: >> >>Can you describe what went wrong with these branches? In particular, >> >>why can the following naive strategy not work: >> >> >> >>1. Make the new system at least as good as the old one. That is >> >>whenever I can write foo.is_bar I can write ask(foo, Q.bar) and I will >> >>get at least as good an answer. In particular Symbol('x', >> >>positive=True) should register automatically in the global assumptions >> >>that x > 0 (if I understand correctly how the new system works...). >> >>2. Replace all queries foo.is_bar by ask(foo, Q.bar). >> >>3. Remove all implementations of the is_bar properties. >> >>4. Remove all remaining remnants of the old system. >> > This is what was largely tried with a branch last summer: >> > - https://github.com/haz/sympy/tree/disconnect-assumptions-2 >> > There was push-back from the community since removing the Symbol('x', >> > positive=True) syntax was largely frowned upon. >> >> I am still very much convinced, that this disconnect-assumptions-2 is >> the simplest and easiest way to get rid of the old assumptions, so >> that we can start speeding up the core, and start using some other >> system for them. >> > BTW, isn't certik/remove_assumptions slightly more recent? Anyway, you
I am not sure at the moment, but the branch I am referring to is the one that Christian worked for about a week during his GSoC. Then the discouragement from the community forced him to stop. > never explained why the old assumptions are slowing us down. Everything > I've seen so far points in the other direction. I claim that no assumptions are faster than assumptions. I claim that the core should not deal with assumptions by default, just like ginac (that Sage uses) doesn't deal with assumptions, and thus is fast. Again, this is necessary in order to achieve the goal of creating a usable CAS (comparable to Mathematica). > >> I would be interested in the community vote on this idea. I vote +1. I >> am aware that Ronan voted -1 last year. What do others think? > > What are you voting +1 on, concretely? Your branch is one year old, so I vote to continue on that branch, which passed almost all tests (rebase it/rework it to the latest master). > it would have to be updated. There were also many test failures Those need to be fixed, just like the ones in the core, that were already fixed. > remaining and it was unbearably slow for complex calculations, what's > your plan for that? As Christian remarked, it was slower if the caching was turned down. Caching is another problem, that needs to be addressed, as Christian remarked. My plan is that preferably the cache should be off by default, and/or flushing it the way Christian did it. If I remember well, it was not slower. Ondrej -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
