| Author | Message | ||||
     Antonio Vargas (toņo) New member Username: toņo Post Number: 1 Registered: 06-2009 |
Hi, I have a great problem to program this model, because i don't know how program the boundary injections, and some equations which depend of those I'm trying to program like definitions. Here is my program and a description of the model that I´m trying to program. I hope you can help me, thanks a lot for your attention.
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| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 1262 Registered: 06-2003 |
Your script does not conform to the syntactic rules for constructing FlexPDE scripts. (You use a parameter U0 which is undefined, your boundary conditions are not in proper form for boundary condition specifications). I suggest you read through the User Guide to FlexPDE and peruse some of the sample problems. You have also chosen the most complex of the forms presented in your journal article as your first attempt at using FlexPDE. You should work through some simpler examples first, and be sure you know how they work and why. | ||||
| Antonio Vargas (toņo) New member Username: toņo Post Number: 2 Registered: 06-2009 |
Hi, I have a problem, I don't know where is the error on the equations or boundaries, only say illegal input. Here is my program again, I hope you can help me and thanks
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| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 1265 Registered: 06-2003 |
There are a multitude of errors in this script. 1) the error that is causing the crash is "log10(-1.8)". Try it on your calculator. [ FlexPDE defends itself less vigorously in the evaluation of constants, on the assumption that direct user entry of an invalid mathematical value will be less common than inadvertent creation of errors in the course of computation. Clearly, we will have to add defense against this kind of entry.] 2) You have, by omission of a COORDINATES section, accepted the default 2D cartesian coordinate system. But your domain layout is 1D. Make up your mind. 3) Similarly, your plots are 2D. This will be acceptable if you convert your domain definition to 2D, but not in 1D. 4) You have used numerous undefined names. 5) You have unmatched parens in many of your equations. 6) You have a factor "((c*Cv)/A)(u)". This is illegal. You need some kind of arithmetic operator between the ")(". You should start out with a simple problem, and try to learn how to use FlexPDE before entering your own creations. Try working through some of our examples, until you know how and why they work. You could also benefit from Professor Backstrom's book "Simple Fields of Physics by FEA". |
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