microsoft-visualbasic-runtime/Extensions/Math/Matrix.vb

#Region "Microsoft.VisualBasic::ed6b97fc29c5ecafbbde6e0d4dc667ac, Microsoft.VisualBasic.Core\Extensions\Math\Matrix.vb"

    ' Author:
    ' 
    '       asuka (amethyst.asuka@gcmodeller.org)
    '       xie (genetics@smrucc.org)
    '       xieguigang (xie.guigang@live.com)
    ' 
    ' Copyright (c) 2018 GPL3 Licensed
    ' 
    ' 
    ' GNU GENERAL PUBLIC LICENSE (GPL3)
    ' 
    ' 
    ' This program is free software: you can redistribute it and/or modify
    ' it under the terms of the GNU General Public License as published by
    ' the Free Software Foundation, either version 3 of the License, or
    ' (at your option) any later version.
    ' 
    ' This program is distributed in the hope that it will be useful,
    ' but WITHOUT ANY WARRANTY; without even the implied warranty of
    ' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ' GNU General Public License for more details.
    ' 
    ' You should have received a copy of the GNU General Public License
    ' along with this program. If not, see <http://www.gnu.org/licenses/>.



    ' /********************************************************************************/

    ' Summaries:

    '     Module MatrixExtensions
    ' 
    '         Function: MatrixMult, ScalarMult
    ' 
    ' 
    ' /********************************************************************************/

#End Region

'     Copyright Jean-Francois Larcher-Pelland 2013-2014
' Distributed under the Boost Software License, Version 1.0.
'    (See accompanying file LICENSE_1_0.txt or copy at
'          http://www.boost.org/LICENSE_1_0.txt)

Namespace Math

    ''' <summary>
    ''' This class contains methods that perform mathematical operations on matrices.
    ''' Operations currently supported are matrix multiplication and scalar multiplication.
    ''' 
    ''' @author Jean-Francois Larcher-Pelland
    ''' </summary>
    Public Module MatrixExtensions

        ''' <summary>
        ''' Multiplies matrices <i>a</i> and <i>b</i> using the brute-force algorithm.
        ''' </summary>
        ''' <param name="a"> The matrix on the left. </param>
        ''' <param name="b"> The matrix on the right. </param>
        ''' <returns> The product of the two matrices. </returns>
        Public Function MatrixMult(a As Double()(), b As Double()()) As Double()()
            If a Is Nothing OrElse b Is Nothing Then
                Throw New ArgumentException("One or both input matrices are null")
            ElseIf a(0).Length <> b.Length Then
                Throw New ArgumentException("Column count of left matrix not equal to row count of right matrix.")
            End If
            Dim row As Integer = a.Length
            Dim col As Integer = b(0).Length
            Dim inner As Integer = b.Length
            Dim out As Double()() = MAT(Of Double)(row, col)
            For i As Integer = 0 To row - 1
                For j As Integer = 0 To col - 1
                    For k As Integer = 0 To inner - 1
                        out(i)(j) += a(i)(k) * b(k)(j)
                    Next
                Next
            Next
            Return out
        End Function

        ''' <summary>
        ''' Performs a scalar multiplication on matrix <i>a</i> using scalar value <i>b</i>.
        ''' </summary>
        ''' <param name="a"> The matrix to be multiplied. </param>
        ''' <param name="b"> Scalar value used in the multiplication. </param>
        ''' <returns> The result of the scalar multiplication. </returns>
        Public Function ScalarMult(a As Double()(), b As Double) As Double()()
            If a Is Nothing Then
                Throw New ArgumentException("Input matrix is null")
            End If
            Dim out As Double()() = MAT(Of Double)(a.Length, a(0).Length)
            For i As Integer = 0 To out.Length - 1
                For j As Integer = 0 To out(0).Length - 1
                    out(i)(j) = a(i)(j) * b
                Next
            Next
            Return out
        End Function
    End Module
End Namespace