[[PageOutline]]

= Application Name =

Matrix Multiplication

= Summary =

* '''Name''': {{{Matrix Multiplication}}}
* '''Contact Person''': {{{support-compss@bsc.es}}}
* '''Access Level''': {{{public}}}
* '''License Agreement''': {{{Apache2}}}
* '''Platform''': {{{COMPSs}}}
* '''Repository''': [[https://compss.bsc.es/svn/bar/tutorial_apps/java/matmul|Matrix Multiplication]]


== Description ==
Matrix multiplication is a binary operation that takes a pair of matrices and produces another matrix.

If A is an n×m matrix and B is an m×p matrix, the result AB of their multiplication is an n×p matrix defined only if the number of columns m in A is equal to the number of rows m in B. When multiplying A and B, the elements of the rows in A are multiplied with corresponding columns in B.

In this implementation, A and B are square matrices (same number of rows and columns), and so it is the result matrix C. Each matrix is divided in N blocks of M doubles. The multiplication of two blocks is done by a multiply task method with a simple three-nested-loop implementation. When executed with COMPSs, the main program generates N^3^ tasks arranged as N^2^ chains of N tasks in the dependency graph.

== Versions ==
There are three versions of Matrix Multiplication, depending on the data types used to store the blocks.
== Version 1 ==
''files'', where the matrix blocks are stored in files.
== Version 2 ==
''objects'', where the matrix blocks are represented by objects.
== Version 3 ==
''arrays'', where the matrix blocks are stored in arrays.

== Execution instructions ==
Usage:
runcompss matmul.files.Matmul <numberOfBlocks> <blockSize>
runcompss matmul.objects.Matmul <numberOfBlocks> <blockSize>
runcompss matmul.arrays.Matmul <numberOfBlocks> <blockSize>

where:
		 * - numberOfBlocks: Number of blocks inside each matrix
		 * - blockSize: Size of each block

== Execution Example ==
runcompss matmul.objects.Matmul 16 4


== Build ==
=== Option 1: Native java ===
cd ~/tutorial_apps/java/matmul/; javac src/main/java/matmul/*/*.java
cd src/main/java/; jar cf matmul.jar matmul/
cd ../../../; mv src/main/java/matmul.jar jar/

=== Option 2: Maven ===
cd ~/tutorial_apps/java/matmul/
mvn clean package