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This effort is still a "work in progress". Please feel free to add comments. BRBut please make the content less visible by using smaller fonts. – Edward J. Yoon

Overview

Hama use a [http://hadoop.apache.org/hbase/ Hbase] to store the matrices – Matrices are basically tables. They are ways of storing numbers and other things. Typical matrix has rows and columns. Actually called a 2-way matrix because it has two dimensions. For example, you might have respondents-by-attitudes. Of course, you might collect the same data on the same people at 5 points in time. In that case, you either have 5 different 2-way matrices, or you could think of it as a 3-way matrix, that is respondent-by-attitude-by-time.

Dense Matrix

For dense matrix computations, The block-partitioned algorithms used to minimize data movement and network cost. Dense Matrix and Blocked Dense Matrix are both stored in one table with other metadata.

– BTW, How to synchronize them? Should we blocking when operate something? – Edward

  // Generate matrix with random elements
  DenseMatrix a = DenseMatrix.random(conf, 1000, 1000);
  DenseMatrix b = DenseMatrix.random(conf, 1000, 1000);
  
  // The type of the Matrix to be blocked, must be dense.
  a.blocking();
  b.blocking();

  DenseMatrix c = a.mult(b);

For example, The matrix multiplication of the original arrays can be transformed into matrix multiplication of blocks as describe below.

C_block(1,1)=A_block(1,1)*B_block(1,1) + A_block(1,2)*B_block(2,1)

C                 A               B
+-----+-----+     +-----+-----+   +-----+-----+
| x x |     |     | --> | --> |   | | | |     |
| x x |     |     | --> | --> |   | ↓ ↓ |     |
+-----+-----+  =  +-----+-----+ * +-----+-----+
|     |     |     |     |     |   | | | |     |
|     |     |     |     |     |   | ↓ ↓ |     |
+-----+-----+     +-----+-----+   +-----+-----+

– To be statically sized blocks, What should we do? – Edward