memory requirement for ode solvers

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Bo 2015-1-15

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https://ww2.mathworks.cn/matlabcentral/answers/170071-memory-requirement-for-ode-solvers

评论： Timmy 2015-1-19

Hi,

I have a large set of ODEs solved by ode45. It works fine but take a bit long. I tried to use other ode solvers and all the stiff solvers generated "out of memory" errors. My question is: what is the memory requirements for the ODE solvers? If no precise answer is possible, do we have some general ideas?

My rough guess is that for the explicit solvers the memory needed is O(N) and the implicit solvers need O(N^2), with N being the number of variables. But I have not found any information about this anywhere.

Bo

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Bo 2015-1-15

编辑：Bo 2015-1-15

I have 16 GB of memory, running Windows 7 64 bit. The problem I am trying to solve is a 2D wave propagation problem with 128x128 for the grid. There are 9 equations to solve. So the total number of equations is 147456, which is a lot.

The error message is just "Out of memory. Type HELP MEMORY for your options."

Timmy 2015-1-19

When you type "memory" on your command window, what does it say?

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Answer 1

Zoltán Csáti 2015-1-16

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编辑：Zoltán Csáti 2015-1-16

I recommend you to discretize first in time and then in space. Then you don't have to handle large number of ordinary differential equations. Or if you insist on this approach, use another solver written by yourself which is less demanding in this case.