NDSolve and memory usage

• To: mathgroup at smc.vnet.net
• Subject: [mg131674] NDSolve and memory usage
• From: Paolo Pani <paolopani at gmail.com>
• Date: Thu, 19 Sep 2013 01:21:44 -0400 (EDT)
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```Hi all,

After some googling, i've found similar problems around, but didn't find a 100% satisfactory answer, so let me ask here:

I'd like to solve a 1+1 problem using the method of lines. In spherical symmetry, I discretize the radial direction and end up with a system of ODEs that I'd like to solve with NDSolve. Problem is, the original 1+1 problem is a system of ~10 first-order PDEs and eventually I need to solve ~10*N first-order ODEs, where N are the radial grid points. To achieve enough resolution, N ranges from O(10^3) to O(10^4).

My problem is that NDSolve requires a lot of memory to solve the system. Also, I need the solution at any time, not only at the final time. What I would like to do is having NDSolve storing intermediate values at each time step in a data file, thus leaving the memory free. Is that possible? Is there any other solution to this problem? Frankly, I find this problem quite restrictive, given that a similar odeint in c would require essentially no memory to run, unless i'm doing some silly mistake of course.

Thanks in advance for the help!
Paolo

```

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