Find the maximum absolute row sum of matrix using MapReduce

The find the maximum absolute row sum of matrix is a good fit with MapReduce model as below.

                                         j=n
The maximum absolute row sum =   max   ( sum | a_{i,j} | ) 
                               1<=i<=n   j=1


- A map task receives a row n as a key, and vector of each row as its value
 - emit (row, the sum of the absolute value of each entries)
- Reduce task select the maximum one

Maybe it can be written in java as below.

  Vector v = givenValue;

  double rowSum;
  for(VectorEntry e : v) {
    rowSum += Math.abs(e.get(i));
  }

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