MATLAB: Element wise multiplication and sum

Question

hi,

i have a matirx a = [1,2,3;4,5,6]; and another matrix b=[2,2,2]

i want to multiply a[i,:].*b where i=1,2 (i.e. the rows of matrix a).

this will result in a matrix y with two rows (with 15 in row1 and 30 in row2)

how do i achieve this efficently without writing a "for" loop.

thanks in advance

Answer 1

I don't know where the 15 came from. I assume you mean 12.

>> a = [1,2,3;4,5,6];
>> b = [2,2,2];
>> a*b.'   % same results as:  sum(a.*[b;b],2)
ans =
      12
      30