[CIG-MC] Fwd: mgunit, levels README correction

Eh Tan tan2 at geodynamics.org
Wed Apr 22 12:01:53 PDT 2009

> "The next four parameters specify the total number of elements for
> the calculation with multigrid solver. The first three give the
> base level grid in each direction, and the fourth parameter "levels"
> indicates how many times it gets doubled. For example, in the sample
> input file input1, mgunitx=6,mgunitz=6,mgunity=6,levels=4, and the
> total number of elements in each direction are 48, i.e., grid size
> of 48x48x48. "  --from README
> If the mgunit value of 6 is doubled 3 times you'd get 48, not 4 times.
>  I think that "levels - 1" is equal to the number of times that mgunit
> is doubled to get the number of elements in a given direction.  After
> looking at some output I think this is correct, but please let me know
> if I'm missing something here.  Thanks for your time everyone.
> -Ethan Fah
Hi Ethan,

Your understanding is correct. The formula used in CitcomCU to construct the mesh size is:

# of elements = mgunit * 2^(levels - 1)

I will clarify those sentences in README.

Eh Tan
Staff Scientist
Computational Infrastructure for Geodynamics
California Institute of Technology, 158-79
Pasadena, CA 91125
(626) 395-1693

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