Check max_pd maximum number polydisperse parameters

[richardh]

Whilst trying to break 2d fitting with oriented elliptical cylinder, which has 6 possible levels of polydispersity integration, three in geometry and three orientation angles, I noted that:

Asking for all 6 gives a "too many polydisperse parameters" message from details.py line 202, (which is fair enough, though perhaps we could increase the allowance). This uses MAX_PD=5 from modelinfo.py

However, asking for 5 levels of integration does not give an error message, but alas plainly does not work, seems to return zero or close to zero from the integrations. Is there a bug somewhere in details.py regarding the buffer spaces or similar. 4 levels of integration seems to work fine.

I have set Paul K as owner as he will likely spot an issue quickly.
Richard

[butler]

That's interesting — I thought Paul had set the maximum to 4 not 5. I believe the reason had to do not only with how slow it gets and unhelpful the answers might be but with some assumptions made in later calculations? Definitely need to engage Paul K. on this.