Работа с векторами в консольном приложении

Module Module1
    Sub Main()
        Dim v1, v2, v3, v4 As Vector
        v1 = New Vector
        v2 = New Vector
        v3 = New Vector
        v4 = New Vector
        v1.x = 3
        v1.y = 4
        v1.z = 6
 
        Dim vv As Double
        Dim d As Double
        d = (v1.Sum(v2)).Mult(v3.Sum(v4))
        vv = v1.mult(v2)
 
    End Sub
End Module

Public Class Vector
    Public x, y, z As Double
 
    Public Sub New(ByVal nx, ByVal ny, ByVal nz)
        x = nx
        y = ny
        z = nz
    End Sub
    Public Sub New()
        x = 0
        y = 0
        z = 0
    End Sub
    Public Function Sum(ByVal v1 As Vector) As Vector
        Dim v As Vector
        v = New Vector()
        v.x = x + v1.x
        v.y = y + v1.y
        v.z = z + v1.z
        Return v
    End Function
 
    Public Function Mult(ByVal v2 As Vector) As Double
        Dim v As Vector
        v = New Vector()
        v.x = x * v2.x
        v.y = y * v2.y
        v.z = z * v2.z
        Return v
    End Function
 
    Public Function Mult(ByVal d As Double) As Vector
        Dim v As Vector
        v = New Vector()
        v.x = x * d
        v.y = y * d
        v.z = z * d
        Return v
    End Function
 
    Public Function ZN() As Vector
        Dim v As Vector
        v = New Vector
        v.x = -x
        v.y = -y
        v.z = -z
        Return v
    End Function
End Class