MatrixNorm - Hama Wiki

Matrix Norms With MapReduce

In examples package of Hama, we have introduced MapReduce-based computing methods for matrix norms.

Maximum absolute column sum
The root of sum of the sum of squares
The maximum absolute row sum
Largest entry in absolute value

Here's the example one of them. Matrix.Norm.One is that find the maximum absolute row sum of matrix.

                                         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

Matrix.infinity, Matrix.Maxvalue and Matrix.Frobenius are almost same with this.