Построение графика в полярных координатах

    Dim X() As Complex
    Dim x0 As Single, y0 As Single, R As Single, FI As Single
    Dim xi(1) As Single, yi(1) As Single
    Dim I As Long
    
    X = OpenDataToComplex('tf.dat')
    Me.Show
    On Error Resume Next
    With Pic
        x0 = .ScaleWidth / 2
        y0 = .ScaleHeight / 2
        For I = 1 To UBound(X)
            R = C.Rho(X(I))
            FI = C.Arg(X(I))
            xi(1) = x0 + R * Cos(FI) * 1000
            yi(1) = y0 - R * Sin(FI) * 1000
            Pic.PSet (xi(1), yi(1)), vbBlue
            Pic.Line -(xi(0), yi(0)), vbBlue
            xi(0) = xi(1)
            yi(0) = yi(1)
        Next I
    End With

Public Function OpenDataToComplex(ByVal FileName As String) As Variant
Dim Fnum As Integer
Dim iCount As Long, lLen As Long
Dim lString As String
Dim byBuffer() As Complex
 
    iCount = 0
    Fnum = FreeFile
    Open FileName For Input Access Read Lock Write As #Fnum
    Do While Not EOF(1)
        iCount = iCount + 1
        Line Input #Fnum, lString
        Do While InStr('0123456789.+- ', Left$(lString, 1)) = 0
            lString = Mid$(lString, 2, Len(lString) - 1)
        Loop
        ReDim Preserve byBuffer(1 To iCount) As Complex
        lLen = InStr(lString, ';')
        byBuffer(iCount).RE = CDbl(Val(Left$(lString, lLen)))
        byBuffer(iCount).IM = CDbl(Val(Right$(lString, Len(lString) - lLen)))
    Loop
    Close #Fnum
    OpenDataToComplex = byBuffer
End Function

Public Type Complex
    Re As Double
    Im As Double
End Type
 
Public Function Cmplx(ByVal Real As Double, ByVal Imag As Double) As Complex
    Cmplx.Re = Real
    Cmplx.Im = Imag
End Function
 
Public Function Polar(ByVal Rho As Double, ByVal Arg As Double) As Complex
    Polar.Re = Rho * Cos(Arg)
    Polar.Im = Rho * Sin(Arg)
End Function
 
Public Property Get Rho(ByRef X As Complex) As Double
    If X.Im = 0 Then
        Rho = Abs(X.Re)
    ElseIf Abs(X.Re) < Abs(X.Im) Then
        Rho = Abs(X.Im) * Sqr(1 + Square(X.Re / X.Im))
    Else
        Rho = Abs(X.Re) * Sqr(1 + Square(X.Im / X.Re))
    End If
End Property
 
Public Property Get Arg(ByRef X As Complex) As Double
Dim A As Double, piDiv2 As Double
 
    piDiv2 = 2 * Atn(1)   'pi/2
    Select Case X.Re
        Case Is > 0
            If (X.Im = 0) Then
                A = 0
            Else
                A = Atn(X.Im / X.Re)
            End If
        Case 0
            Select Case X.Im
                Case Is > 0: A = piDiv2
                Case 0:      A = 0
                Case Is < 0: A = -piDiv2
            End Select
        Case Is < 0
            Select Case X.Im
                Case Is > 0: A = Atn(X.Im / X.Re) + 2 * piDiv2
                Case 0:      A = 2 * piDiv2
                Case Is < 0: A = Atn(X.Im / X.Re) - 2 * piDiv2
            End Select
    End Select
    Arg = A
End Property