# Multiply each element with a column from a matrix

Suppose I have a matrix B, where its elements are b_ij(i-th row, j-th column).
I have another matrix U, where its columns are u_j(j-th column).

How can I multiply each b_ij with respect to column u_j in U, then sum up all the results in each row of B? (that is, $\sum b_{ij}u_j$ for each i)

Thanks.

Let me see if I get your problem right: are you talking something like this?

b = b.view(1,-1)
for i in range(col_u):
sum = 0
for j in range(length(b)): # iterating through cols in u
sum += b[j]* u[: , i]

A[i,:] = sum


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I am so sorry. I had some typo in the previous version. A is a typo, I am trying to sum up the result for each row of B. Thanks for your response

Yes, I think you got it. Except for the j, I think it should be in range(col_B * i+1, col_B * (i+1) + 1)