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Re: multiplying matrices into tensors?
From: |
James Cloos |
Subject: |
Re: multiplying matrices into tensors? |
Date: |
Thu, 04 Aug 2011 16:36:00 -0400 |
User-agent: |
Gnus/5.110018 (No Gnus v0.18) Emacs/24.0.50 (gnu/linux) |
>>>>> "JGH" == Jordi Gutiérrez Hermoso <address@hidden> writes:
JGH> This can still be done with bsxfun, but takes one more line:
JGH> c = bsxfun(@times, permute(a, [1,2,3]), permute(b(4,:),[3,1,2]))
JGH> c(1:3,:,:) += bsxfun(@times, permute(b(1:3,:), [1,3,2]),
JGH> permute(a(4,:), [1,2,3]))
JGH> Note that permute(..., [1,2,3]) is superfluous. I just put in place
JGH> to make it explicit how the indices of a and b correspond to the
JGH> indices of c.
I figured that out, and left it in for the same reason.
I already wrote an hmult function, which also worked, and which can deal
with R^{n}P, not just R^{3}P. I just need to flesh it out to use varargin
and add code for other functions on homogeneous coords before packaging it.
Thank you. Your explanations and examples helped!
-JimC
--
James Cloos <address@hidden> OpenPGP: 1024D/ED7DAEA6