sbh

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16 years, 65 days

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These are answers submitted by sbh

Yes, that is what I got basically when I split it into two first-order eqns. I guess the result you predict, that it is most likely unsolvable analytically, manifests when I try to execute the solution to zs(r) subs({v=diff(zs(r),r)},%) dsolve(%) resulting in the integral of a "RootOf" expression -> unevaluated. Thanks a lot for all the help. I have installed your library off your webpage too! Steve
Well that was the problem - I changed the variable name from "zeta" to "z" and, of course, it worked! Thanks Alec, Acer and Axel for the really quick help in what was a very simple mistake. Steve
I see. Well that is good to know and I was sure there wasn't anything wrong with what I wrote..... Maybe my Mac is angry at me. Do you, or anyone reading this, have the ability to try it out on Maple 11? I was not really planning on buying 12 yet. Thanks for trying it out on 12 and any future help, Steve

Thanks Robert,

That was indeed a good way to go.  Thanks a lot for your quick reply,

Steve

Thanks a lot Robert for the help - I did it exactly that way and aside from some momentary parsing errors it works fine. It has two procedures local to the main one that defines the ODE system - functions that return the first and second derivatives based on stencils. When I carry out the integration to, say, 1.0 it is fine but if I carry it out further it acquires a lot of "Memory: xxx" and "Time: xxx". I saw in other posts that you had helped someone with the exact same error message I now get for these "long" times, "...kernel connection lost...". Aside from optimizing the code, is there any other way (via systems tools, etc) that this can be worked around? Like other postings I have 2GB of memory but that is never maxed and other reasons tell me that memory isn't really the issue. Also firewall problems are not likely either since all specified *.exe's are allowed exceptions. Thanks for any advice you may have about this new problem and thanks again for the help up to this point. Cheers, Steve
Hello, been out of country on for a while..... Anyways, thanks for the advice. However, I tried the above and it states, "Error, (in dsolve/numeric) input 'procedure' is not properly defined. The input solution values (third argument) cannot be changed. See ?numeric,IVP for details." I get similar systems of equations to work if I define them like; YP[1]:=.....; YP[2]:=.....; YP[3]:=..... .... YP[10]:=....; but if I need 100 ODEs I can't write them allout. I will try to upload the file so that it might help with my question. Thanks again. Steve Please replace this text with the link to your file. View 1620_Copy 2 of PDEsolverMOL.mw on MapleNet or Download 1620_Copy 2 of PDEsolverMOL.mw
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Hello, been out of country on for a while..... Anyways, thanks for the advice. However, I tried the above and it states, "Error, (in dsolve/numeric) input 'procedure' is not properly defined. The input solution values (third argument) cannot be changed. See ?numeric,IVP for details." I will try to upload the file so that it might help with my question. Thanks again. Steve Please replace this text with the link to your file. View 1620_Copy 2 of PDEsolverMOL.mw on MapleNet or Download 1620_Copy 2 of PDEsolverMOL.mw
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Hello JacquesC, Thanks so much for the help. I tried that and I also attached the file so that people can see it. I guess the real error seems to be "...output derivative values (fourth argument) must be used in-place...." I believe then that Maple 11 wants the right-hand side of each equation literally spelled out - which is a pain if there are many equations. Do you, or anyone else, know of a way to skirt this issue? Thanks again and please excuse me for the long Memorial weekend break! :) Steve View 1620_Copy 2 of PDEsolverMOL.mw on MapleNet or Download 1620_Copy 2 of PDEsolverMOL.mw
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