# Element wise (.*) in Simulink for two matrices with different dimensions

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Hammadi Jaiem on 27 Feb 2023
Edited: Fangjun Jiang on 27 Feb 2023
Let Anxm and Bnx1 be two matrices with different dimensions
On Matlab: element-wise multiplication ie. A.*B = a Cnxm Matrix with no errors.
Example:
[1 2 3; 4 5 6;] .* [1; 0] = [1 2 3; 0 0 0]
However on Simulink If I use the Product block set on element-wise multiplication on A and B I get mismatch widths or dimensions Error.
Note that If I used a Matlab function Block on Simulink that calls A.*B. I am able to get the result I need. but I am looking for a solution that does not use the matlab function Block. Please share any solution you might think of.
Thanks!

Fangjun Jiang on 27 Feb 2023
Edited: Fangjun Jiang on 27 Feb 2023
a=[1 2 3; 4 5 6];
b=[1; 0];
a.*b
ans = 2×3
1 2 3 0 0 0
This is a change made in MATLAB in R2016b when implicit expansion is introduced. Prior to R2016b, it will cause a "size mismatch" error.
Simulink does not have similar change to make it be supported by its blocks, as far as R2022b.
To make a block diagram work, and with your existing data "b", you will have to expand it yourself through another block
c=ones(1,3);
a.*(b*c)
ans = 2×3
1 2 3 0 0 0

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