Timeline for ndsz : step size is effectively zero; singularity or stiff system suspected
Current License: CC BY-SA 4.0
13 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 16, 2020 at 9:23 | history | edited | CommunityBot |
Commonmark migration
|
|
| Sep 26, 2019 at 7:49 | history | edited | xzczd♦ | CC BY-SA 4.0 |
added 154 characters in body
|
| Jul 3, 2017 at 16:11 | comment | added | bbgodfrey |
Informative comparison (+1). It prompted me to run your code again, but this time with my renormalized ODE. Instead of returning unevaluated, it failed with the all too common zero step-size error, even when I used the separatrix solution as the boundary condition and initial guess at xfn..
|
|
| Jul 3, 2017 at 6:08 | history | edited | xzczd♦ | CC BY-SA 3.0 |
added 1 character in body
|
| Jul 3, 2017 at 6:01 | comment | added | xzczd♦ | @bbgodfrey The 2 solutions are (acceptably) consistent, see my update. OK, time to write back to WRI. | |
| Jul 3, 2017 at 5:59 | history | edited | xzczd♦ | CC BY-SA 3.0 |
added 626 characters in body
|
| Jul 3, 2017 at 4:41 | comment | added | bbgodfrey | It might be useful to compare your "Shooting" answer with the one I just posted to see whether the claim by Wolfram, Inc that the former method involved too large an error for this problem is accurate. I cannot make the comparison myself, because I do not have version 9 of Mathematica. | |
| Jun 21, 2017 at 12:32 | comment | added | xzczd♦ |
…Then in the attachment of the response the following code is used to check the error: Plot[eqn[[1]] /. s // Evaluate, {x, x0, xf}], it does show a large error, but… I should say I feel bit unconvinced about this response, because I roughly remember, there exists example indicating that, checking error in this way may be too rigorous for nonlinear ODEs, but I can't find it at moment so can't launch an effective "counterattack"…
|
|
| Jun 21, 2017 at 12:23 | comment | added | xzczd♦ | @bbgodfrey Response from WRI: "Thank you for contacting Wolfram Technical Support. I understand that for the example in the notebook you sent in, NDSolve evaluates in version 9, but no longer evaluates in version 11. It appears that the result returned in version 9 does not satisfy the equation. To prevent returning a wrong result, between version 9 and 11 more stringent error checks must have put in place so that NDSolve would return unevaluated instead of returning a wrong result in cases like this. "… | |
| Jun 20, 2017 at 1:51 | comment | added | bbgodfrey | That is what I feared. I hope that you report it to Wolfram, Inc. Best wishes. | |
| Jun 20, 2017 at 1:48 | comment | added | xzczd♦ | @bbgodfrey So we found another backslide… The code works well in v9.0.1 on Win10. | |
| Jun 19, 2017 at 20:04 | comment | added | bbgodfrey |
NDSolve returns unevaluated, when I run your code. I am using 11.1.1 on Windows 10.
|
|
| Nov 4, 2016 at 13:51 | history | answered | xzczd♦ | CC BY-SA 3.0 |