# How to multiply row of matrix A with column of matrix B?

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Kalasagarreddi Kottakota on 24 Nov 2021
Edited: James Tursa on 25 Nov 2021
A is 121 x 36 matrix
B is 36 x 121 matrix
The result C should be 121 x 1 matrix.
May I know how should I multiply a row of A with col of B? so that resulting matrix is 121 X 1.
##### 2 CommentsShowHide 1 older comment
Adam Danz on 24 Nov 2021
Prehaps the goal is the multiply a col of A by row of B.

James Tursa on 25 Nov 2021
Edited: James Tursa on 25 Nov 2021
Maybe this is what you want?
C = sum(A .* B.',2)

### More Answers (1)

the cyclist on 24 Nov 2021
If @Adam Danz is correct that you actually want to multiply all the elements of one column of A with one row of B, then
% Define A and B
A = rand(121,36);
B = rand(36,121);
% Which row and column?
colA = 2;
rowB = 3;
% Multiply the selected row and column
V = A(:,colA) .* B(rowB,:).'; % <----- Note that I used the transpose here
% Check the size of V
size(V)
ans = 1×2
121 1

R2021b

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