Absolute tolerance scale in RxD

Extending NEURON to handle reaction-diffusion problems.

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Absolute tolerance scale in RxD

Post by bschneiders »

I have been getting numerical errors when simulating my model in RxD, and I think they are due to scaling within CVode. I've seen how to use the absolute tolerance scale multiplier for species specified in MOD files (https://www.neuron.yale.edu/neuron/stat ... .atolscale) and am using the following code in any MOD files containing calcium:

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      ca    (mM)  <1e-6> 
However, is there a way to set this scale for RxD species as well? While calcium is in my calcium channels and pump MOD files and can therefore be scaled there, I have several RxD species in my model that don't come up in MOD files (i.e. a calcium buffer), but they still need to be scaled. Any suggestions on how to do so?

See the following for a plot of the error I'm talking about (the image wouldn't display so here is the URL):
Posts: 225
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Location: Yale School of Public Health

Re: Absolute tolerance scale in RxD

Post by ramcdougal »

I just added this functionality to the development branch.

Get a copy via

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git clone https://github.com/ramcdougal/nrn.git
and then compile as normal.

Specify an atolscale when you define the rxd.Species, e.g.

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ca = rxd.Species(cyt, initial=0, atolscale=1e-3)
(If you've already set cvode.atol to 1e-3, this means that it would try to compute calcium to an absolute accuracy of 1e-6.)
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