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Multiply a "stack" of matrices with a "stack" of vectors

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Michael
Michael 2014-3-4
评论： James Tursa 2014-3-7
I have a matrix 2 x 2 x n and a vector 2 x n. So basically, I have n layers of 2 x 2 matrices and n layers of vectors with 2 entries. I d like to do a matrix-vector multiplication on each layer.
I could easily do this using a for loop, but is there a way which directly supports such an operation?

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Jos (10584)
Jos (10584) 2014-3-4
编辑：Jos (10584) 2014-3-7
One option:
n = 6
% M is your 2x2xn array of "matrices
M = rand(2,2,n)
% V is your 2xn array of "vectors"
V = rand(2,n)
fh = @(k) M(:,:,k) * V(:,k)
C = arrayfun(fh,1:n,'un',0)
C2 = cat(3,C{:})
Corrected.
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Jos (10584)
Jos (10584) 2014-3-7
You did ask for " a way which directly supports such an operation ", not for a faster way! ;-)
To be honest, I think a straight forward for-loop is as good as the accumarray approach in this case.
James Tursa
James Tursa 2014-3-7
If you want speed, I would suggest looking at one of the solutions I have posted.

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James Tursa
James Tursa 2014-3-4
编辑：James Tursa 2014-3-7

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