Timeline for Reaction-diffusion PDE with NDSolve: either very slow or very inaccurate
Current License: CC BY-SA 3.0
4 events
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| Apr 21, 2016 at 7:50 | comment | added | Tamás Czárán | Yes, that may be the problem here: the integral is often very close to zero. Is there a way to tell NIntegrate to set it to zero after a certain number of evaluation attempts, and go on? Of course it should not miss the spikes in the meantime - maybe these two criteria cannot be met simultaneously... | |
| Feb 23, 2016 at 14:00 | comment | added | Anton Antonov | @TamásCzárán Integral estimation with sampling points and fitted polynomials has difficulties applying reliably stoping criteria based on precision and accuracy goals when the integral is close to zero. NIntegrate would not know that the integral is zero, may be the integral value is just small. Also, NIntegrate does try to evaluate several scenarios when the integral seems to be zero is it really zero. | |
| Feb 15, 2016 at 11:06 | comment | added | Tamás Czárán | Thanks a lot, Anton! I'm going to check the NIntegrateSamplingPoints option out, it looks like a promising approach indeed. I'm still baffled how your Mathematica could NDSolve the system without the MaxStepSize option set - mine (ver. 10.3) couldn't... But removing the t=0 solution is a good idea - there the problem is that F is indeed 0 all over the integration domain, so the complaint of NIntegrate is justified (even if I don't really see why this should be so - the integral of the constant zero function should be zero, without complaints). Thank you once again! | |
| Feb 12, 2016 at 14:26 | history | answered | Anton Antonov | CC BY-SA 3.0 |