Sub Pgm()
    Const Rbegin = "B2"
    Const N = 100
    
    ReDim Y(N, 1)
    
    Dim ab, a_b, L2, Delta
    ab = InputBox("Введите значения интервала a b" + vbCrLf + vbCrLf + "(образец приведен)", "Ввод данных", "-1,2   7,2")
    
    If Len(ab) = 0 Then Exit Sub
    
    a_b = Split(Replace(ab, ".", ","), " ")
    L2 = UBound(a_b)
    
    If L2 < 1 Then
        MsgBox "Интервал не введен" + vbCrLf + vbCrLf + """" + ab + """"
        Exit Sub
    End If
    
    If Not IsNumeric(a_b(0)) Or Not IsNumeric(a_b(L2)) Then
        MsgBox "Значения интервала не корректны" + vbCrLf + vbCrLf + """" + a_b(0) + """   """ + a_b(L2) + """"
        Exit Sub
    End If
    
    a_b(0) = CDbl(a_b(0))
    a_b(L2) = CDbl(a_b(L2))
    Delta = (CDbl(a_b(L2)) - CDbl(a_b(0))) / N
    
    For i = 0 To N
        Y(i, 0) = a_b(0) + Delta * i
        Y(i, 1) = Func(a_b(0) + Delta * i)
    Next

    Sheets.Add After:=Sheets(Sheets.Count)
    Range(Rbegin + ":" + Range(Rbegin).Offset(N, 1).Address) = Y
    
    Dim NameList, Rdann, Rarg
    NameList = ActiveSheet.Name
    
    Rarg = Range(Rbegin).Offset(0, 0).Address + ":" + Range(Rbegin).Offset(N, 0).Address
    Rdann = Range(Rbegin).Offset(0, 1).Address + ":" + Range(Rbegin).Offset(N, 1).Address

    ActiveSheet.Shapes.AddChart.Select
    ActiveChart.ChartType = xlLine
    ActiveChart.SetSourceData Source:=Range(NameList + "!" + Rdann)
    
    ShapeName = ActiveSheet.Shapes(1).Name
    
    With ActiveSheet.Shapes(ShapeName)
        .ScaleWidth 1.3, msoFalse, msoScaleFromBottomRight
        .ScaleHeight 1.2, msoFalse, msoScaleFromBottomRight
        .ScaleWidth 1.3, msoFalse, msoScaleFromTopLeft
        .ScaleHeight 1.2, msoFalse, msoScaleFromTopLeft
    End With
    
    With ActiveChart
        With .Axes(xlCategory)
            .Select
            .TickMarkSpacing = 5
            .TickLabelSpacing = 5
            .AxisBetweenCategories = False
            .CrossesAt = 1
            .HasMajorGridlines = True
        End With
        .PlotArea.Select
        .SeriesCollection(1).XValues = "=" + NameList + "!" + Rarg
    End With
    Range(Rarg).NumberFormat = "0.00"
    Range("A1").Select
End Sub

Function Func(x)
    If x < -1 Then Func = 0
    If -1 <= x And x < 0 Then Func = Cos(x * 3.14159265358979)
    If 0 <= x And x < 2 Then Func = x ^ 2 + 1
    If 2 <= x And x < 7 Then Func = 7 - x
    If x >= 7 Then Func = 0
End Function