簡易行列計算

Matrix.vb

Public Class Matrix

    ''' <summary>
    ''' 乗算
    ''' </summary>
    Public Shared Function Multiply(multiplicandMatrix As Double(,),
                                    multiplierMatrix As Double(,)) As Double(,)

        Dim matA = multiplicandMatrix
        Dim matB = multiplierMatrix

        ' 行数/列数確定
        Dim L = matA.GetUpperBound(0)
        Dim M = matA.GetUpperBound(1)
        If M <> matB.GetUpperBound(0) Then
            Throw New Exception("被乗数の列の個数と、乗数の行の個数が違います")
        End If
        Dim N = matB.GetUpperBound(1)

        ' 結果用
        Dim matR(L, N) As Double

        ' 乗算
        For i = 0 To L
            For j = 0 To N
                For k = 0 To M

                    matR(i, j) += matA(i, k) * matB(k, j)

                Next
            Next
        Next

        Return matR
    End Function

    ''' <summary>
    ''' 逆行列
    ''' </summary>
    Public Shared Function Inverse(regularMatrix As Double(,)) As Double(,)

        Dim matA = regularMatrix
        Dim N = matA.GetUpperBound(0)

        Dim matR = E(N + 1)

        For i = 0 To N

            Dim a = matA(i, i)

            ' 除算
            For j = 0 To N
                matA(i, j) /= a
                matR(i, j) /= a
            Next


            ' 掃出し
            For j = 0 To N
                If (j <> i) Then
                    Dim b = matA(j, i)

                    For k = 0 To N
                        matA(j, k) -= matA(i, k) * b
                        matR(j, k) -= matR(i, k) * b
                    Next
                End If
            Next
        Next

        Return matR
    End Function

    ''' <summary>
    ''' 単位行列
    ''' </summary>
    Public Shared Function E(degree As Integer) As Double(,)

        Dim N = degree - 1
        Dim matR(N, N) As Double

        For i = 0 To N
            matR(i, i) = 1
        Next

        Return matR
    End Function

    ''' <summary>
    ''' 転置行列
    ''' </summary>
    Public Shared Function Transpose(matA As Double(,)) As Double(,)

        Dim M = matA.GetUpperBound(0)
        Dim N = matA.GetUpperBound(1)

        Dim matR(N, M) As Double

        For i = 0 To M
            For j = 0 To N
                matR(j, i) = matA(i, j)
            Next
        Next

        Return matR
    End Function

End Class