MATLAB Answers

How to do matrix or table multiplication?

3 views (last 30 days)
Hi,
I have this two tables or matrix, where i am looking to perform the addition of 1st element in the first matrix of first row with the all element in the first row of second matrix and similarly with the second element in the first matrix of first row with the all the elements of first row in second matrix. Similarly with the second and third row elements.
Is there any easy way or formula to do this? even if the size of the matrix changes
Example:
IntakeTable = [0 3 2
4 2 2
4 4 4 ];
ExhaustTable = [0 3 2
4 2 2
2 2 2 ];
resultTable =[0+0 0+3 0+2 3+0 3+3 3+2 2+0 2+3 2+2
4+4 4+2 4+2 2+4 2+2 2+2 2+4 2+2 2+2
4+2 4+2 4+2 4+2 4+2 4+2 4+2 4+2 4+2]

  0 Comments

Sign in to comment.

Accepted Answer

Walter Roberson
Walter Roberson on 6 Sep 2019
resultTable = kron(IntakeTable,ones(1,size(ExhaustTable,2))) + repmat(ExhaustTable,1,size(IntakeTable,2));

  1 Comment

Sign in to comment.

More Answers (2)

Bjorn Gustavsson
Bjorn Gustavsson on 6 Sep 2019
Looping seems simplest and most easily readable for humans:
szI = size(IntakeTable);
szE = size(ExhaustTable);
resultTable = zeros(size(ExhaustTable,1),size(ExhaustTable,2)*size(IntakeTable))
for i1 = 1:szI(2),
resultTable(:,(1:szE,2)+(i1-1)*szE(2)) = repmat(IntakeTable(:,i1),1,szE(2)) + ...
ExhaustTable;
end
HTH

  1 Comment

Sign in to comment.


Adam Danz
Adam Danz on 6 Sep 2019
Edited: Adam Danz on 6 Sep 2019
resultTable = repmat(ExhaustTable,1,3) + repelem(IntakeTable,1,3)
Or, if the number of columns vary,
resultTable = repmat(ExhaustTable,1,size(IntakeTable,2)) + repelem(IntakeTable,1,size(ExhaustTable,2))

  1 Comment

Sign in to comment.

Sign in to answer this question.