ExMatrix

ExMatrix is an Elixir library implementing a parallel matrix multiplication algorithm with other utilities for working with matrices.

Installation

The latest version is 0.0.1 and requires Elixir ~> 1.0.

Releases are published through hex.pm. Add as a dependency in your mix.exs file:

defp deps do
  [ { :exmatrix, "~> 0.0.1" } ]
end

Matrices

Matrices are expected to be lists of lists of numbers, so for example, a simple 2x2 matrix might look like

iex> matrix = [[0, 0], [1,1]]
[[0, 0], [1,1]]

To get an empty matrix you can use new_matrix to generate a zero-filled matrix

iex> ExMatrix.new_matrix(2,2)
[[0, 0], [0,0]]

To test out the library, you can generate a random matrix using random_cells by passing the number of rows, columns and a maximum value to be contained in each cell.

iex> random_cells(2, 2, 10)
[[3, 4], [9, 0]]

Multiplication

To multiply two matrices together you can call either multiply or pmultiply if you wish to do the multiplication in parallel.

iex> matrix_a = [[2,3], [3,5]]
[[2,3], [3,5]]
iex> matrix_b = [[1,2], [5,-1]]
[[1,2], [5,-1]]
iex> ExMatrix.muliply(matrix_a, matrix_b)
[[17, 1], [28, 1]]

Addition

Addition of matrices happens as you might expect, with the add function

iex> matrix_a = [[0, 1, 2], [9, 8, 7]]
[[0, 1, 2], [9, 8, 7]]
iex> matrix_b = [[6, 5, 4], [3, 4, 5]]
[[6, 5, 4], [3, 4, 5]]
iex> ExMatrix.add(matrix_a, matrix_b)
[[6, 6, 6], [12, 12, 12]]

If you provide two matrices where the number of rows or columns differs, then an ArgumentError is raised.

Subtraction

Subtraction is performed on two matrices (which must have the same dimentions) by using the subtract function

iex> matrix_a = [[0, 1, 2], [9, 8, 7]]
[[0, 1, 2], [9, 8, 7]]
iex> from_matrix = [[6, 5, 4], [3, 4, 5]]
[[6, 5, 4], [3, 4, 5]]
iex> ExMatrix.subtract(matrix_a, from_matrix)
[[-6, -4, -2], [6, 4, 2]]

If you provide two matrices where the number of rows or columns differs, then an ArgumentError is raised.

Utility functions

Size

The size function will return the number of rows and columns in your matrix.

iex> {rows, cols} = ExMatrix.size([[1,2,3], [4, 5, 6], [7, 8, 9]])
{3, 3}
iex> rows
3

Transpose

You can transpose a matrix so that the columns become rows (rotating the matrix by 90 degrees).

iex> ExMatrix.transpose([[1,2,3], [4, 5, 6], [7, 8, 9]])
[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

License

   Copyright 2015 A115 Ltd

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.