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Re: [SCIRUN-USERS] Stiffness Matrix

Chronological Thread 
  • From: David Weinstein <>
  • To: "Svendsen, Mark C" <>
  • Cc: <>
  • Subject: Re: [SCIRUN-USERS] Stiffness Matrix
  • Date: Thu, 22 Sep 2005 11:18:21 -0600

Hi Mark,

Since conductivity is the inverse of resistance, you just need to take the inverse of each of the conductivity tensors. The lookup table has this format:

    C1xx C1xy C1xz C1yx C1yy C1yz C1zx C1zy C1zz
    C2xx C2xy C2xz C2yx C2yy C2yz C2zx C2zy C2zz
    Cnxx Cnxy Cnxz Cnyx Cnyy Cnyz Cnzx Cnzy Cnzz

To build a comparable resistance table, you would want to turn each row into a 3x3 matrix, and then invert it. However, for the case of the UtahTorso model, all of the tensors are isotropic (i.e. the first, middle, and last columns of that table are identical, and all other columns are zero) -- so you can just take the first column and replace each value with 1/value. A simple SCIRun network to do this is:

SCIRun::DataIO::FieldReader (1) -> (1) BioPSE::Modeling::ModifyConductivities (2) -> (1) SCIRun::Math::MatrixSelectVector (1) -> (1) SCIRun::Math::LinAlgUnary

[I'm using parentheses to indicate port number, e.g. (4) MyModule (3) means connect the data from the previous module into input port 4 of MyModule, and then pass the result from MyModule's output port 4 to the next module.]

On the LinAlgUnary UI, select "Column" (instead of "Row"), and on the LinAlgUnary UI, type this into the Function text entry:


On Sep 22, 2005, at 7:13 AM, Svendsen, Mark C wrote:

Hello Everyone

I was wondering if instead of extracting the conductivity matrix for the FE torso, could I extract a resistivity matrix for the FE torso? Is there a resistivity lookup table, as compared to the conductivity table?

Thank you.


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