VB.NET Matrix Arithmetic Example

Imports System

Imports CenterSpace.NMath.Core

Namespace CenterSpace.NMath.Core.Examples.VisualBasic

  ' A .NET example in VB.NET showing the element-wise operators overloaded for
  ' matrix/matrix and matrix/scalar operations.
  '
  ' The arithmetic operators +,-,*,/ are overloaded
  ' for matrix-matrix and matrix-scalar operations. These operators
  ' have their usual meanings. For example, if A, B, and C are
  ' matrices, s is a scalar and op is one of +,-,*,/, then
  ' 
  '   C = A op B
  '   
  ' produces a matrix C such that
  ' 
  '   C[i,j] = A[i,j] op B[i,j]
  '   
  ' and 
  ' 
  '   C = s op B
  '   
  ' produces a matrix C such that
  ' 
  '   C[i,j] = s op B[i,j].
  Module MatrixArithmeticExample

    Sub Main()

      Console.WriteLine()

      Dim rows As Integer = 3
      Dim cols As Integer = 3

      ' Create a matrix containing all (1,0)'s
      Dim A As New DoubleComplexMatrix(rows, cols, New DoubleComplex(1, 0))
      ' Create a matrix containing all (0,1)'s
      Dim B As New DoubleComplexMatrix(rows, cols, New DoubleComplex(0, 1))
      Console.WriteLine("A = {0}", A.ToString())
      Console.WriteLine("B = {0}", B.ToString())

      ' Adding them together will yield a matrix of the same size containing 
      ' all (1,1)'s
      Dim S As DoubleComplexMatrix = A + B
      Console.WriteLine("A + B = {0}", S.ToString())

      ' Vector scalar operators are also provided.
      Dim c As New DoubleComplex(2, 0)

      ' Produces a matrix containing all (1,2)'s
      Dim aSum As DoubleComplexMatrix = A + (c * B)
      Console.WriteLine("A + c*B = {0}", aSum.ToString())

      ' If we increase the number of rows of A and try to multiply with B, we
      ' will get a MismatchedSizeException. Matrices must have the same
      ' dimensions to be combined using the element-wise operators.
      A.Resize(rows + 1, cols)
      Dim P As DoubleComplexMatrix
      Try
        P = A * B
      Catch e As MismatchedSizeException
        Console.WriteLine("Oops - " + e.Message)
      End Try

      ' Put A back the way it was.
      A.Resize(rows, cols)

      ' Increment and decrement operators have been overloaded too
      ' (for real types only).
      Dim Areal As DoubleMatrix = NMathFunctions.Real(A)
      Console.WriteLine("Areal = {0}", Areal.ToString())
      Areal = DoubleMatrix.Increment(Areal)
      Console.WriteLine("Areal++ = {0}", Areal.ToString())

      Console.WriteLine()
      Console.WriteLine("Press Enter Key")
      Console.Read()

    End Sub

  End Module

End Namespace