Hi all,

I was wondering how to go about doing a matrix-vector multiplication using

hadoop. I have my matrix in one file and my vector in another. All the map

tasks will need the vector file... basically they need to share it.

Basically I want my map function to output key-value pairs (i,m[i,j]*v(j)),

where i is the row number, and j the column number; v(j) is the jth element

in v. And the reduce function will sum up all the values with the same key -

i, and that will be the ith element of my result vector.

I don't know how to format the input to do this.. even if I do it in 2 MR

iterations, first formatting the input and second the actual

matrix-vector-multiply, I don't have a clear idea.

If you have any ideas/suggestions I would appreciate it!

Thanks in advance,

Alexandra