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bnmurphy / PMCAMx-2008

This Repository is for testing version control between SU, Patras, and CMU
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memory requirements #4

Closed sebarn closed 10 years ago

sebarn commented 10 years ago

when we were talking about memory requirements, you mentioned that the arrays need to be something like

100 x 100 x 50 x 30 x something x something

is that a tensor of rank 6 or (i.e. a 100x100x50 matrix each matrix element having 30 and each of those having something and so forth)?

what is the stuff that is inside? I guess real numbers? single or double precsision?

bnmurphy commented 10 years ago

Double precision

It's typical to run on a 140x140 horizaontal domain. 14-20 layers are common. And the number of chemical species is usually around 500. So that's a rank 4 matrix. We rarely have any problems with RAM for PMCAMx-2008

The memory issues get worse for PMCAMx with PSAT (which I have not uploaded yet). We add to the Rank 4 matrix an extra dimension tracking the source of each chemical species. This makes it rank 5 with the 5th dimension having size up to 15 in previous incarnations. We'd love to make it bigger though.

sebarn commented 10 years ago

ok, I'll run a test small test to compute the memory requirements for this in C next week. this is the same for C and Fortran (I really should start learning that ;))