1,365 reputation
621
bio website
location
age
visits member for 2 years, 2 months
seen 16 hours ago

Mar
28
accepted NIntegrate is resetting my variables and not giving me a result?
Mar
28
comment NIntegrate is resetting my variables and not giving me a result?
@SjoerdC.deVries Oh...you are saying x,y,z are local to NDSolve? It does make sense.. But this has actually worked on this? I am not a mathematician at all neither am I into programming so I don't have your keen eye to say that this is ugly! :)
Mar
28
revised NIntegrate is resetting my variables and not giving me a result?
Provided error message.
Mar
28
revised NIntegrate is resetting my variables and not giving me a result?
deleted 2 characters in body
Mar
28
comment NIntegrate is resetting my variables and not giving me a result?
@rcollyer did that. Still is an ugly mass of text. Boy mathematica sure can be an ugly environment. Anyway...
Mar
28
revised NIntegrate is resetting my variables and not giving me a result?
Tried to reduce the quantity of text.
Mar
28
comment NIntegrate is resetting my variables and not giving me a result?
@R.M Yes, I realize that. I don't know where else I could post the code itself so as to focus on the problem that the code is stricken by here! :(
Mar
28
comment What does MaxStepFraction do?
This makes sense, thank you.
Mar
28
asked NIntegrate is resetting my variables and not giving me a result?
Mar
28
accepted What does MaxStepFraction do?
Mar
28
revised What does MaxStepFraction do?
Correcting an error.
Mar
28
comment What does MaxStepFraction do?
@F'x I apologize. I am getting careless. I meant MaxStepFraction and NOT MaximumStepFraction. I've also included some more thoughts about this option in EDIT 2.
Mar
28
revised What does MaxStepFraction do?
edited body
Mar
28
revised Setting the DifferenceOrder Option
There was also a syntax error in my mathematica program. I thought adding the "syntax" tag would draw attention to that.
Mar
28
accepted Setting the DifferenceOrder Option
Mar
28
comment Setting the DifferenceOrder Option
Yes thats exactly what I did -- set the "MaxDifferenceOrder"->1. I find that now, I get better convergence than the authors by decreasing the "MaxStepFraction". Forgive me as I am a sophomore at mathematica and I did post a further question about "MaxStepFraction" here! :( but I am getting closer to understanding NDSolve better.
Mar
28
asked What does MaxStepFraction do?
Mar
28
comment Setting the DifferenceOrder Option
Sure thing! The results I am trying to compare with are here. The authors have used a Backward Euler method for their nonlinear equation. I read from a couple of books that the Backw'd Euler method is actually the BDF method to order 1 and hence I am trying to implement the same.
Mar
28
comment Setting the DifferenceOrder Option
that makes sense considering that it's called the "MaxDifferenceOrder". But it is rather unfortunate that I can't quite change the order and fix it manually. That makes comparison with published results and consequently publishing my results virtually impossible.
Mar
28
comment Setting the DifferenceOrder Option
I find that fixing the "MaxDifferenceOrder" in BDF does have an effect on the result. A higher order did get me closer to the solution. I hope I am not understanding that all wrong! :P