difference between interpolated values

[Aligator]

Hi,
I have a chart with two series, X bootom is date time, Y is numeric. I must display the caculated difference betwwen the 2 series when I move the cursor accross one of the serie. Is this possible to get this calculated value between two points ? how ? ... thanks
JP

[Edu]

Hi Aligator

You have to calculate the difference in the "OnMouseMove" event. You have got two ways to calculate the difference:

1- You can use the Subtract Function, and hide the line but catch the points.
2- You can calculate the difference between two series, doing the subtract with the two Y values, as below code:

Code: Select all

Private Sub Form_Load()
    TChart1.Series(0).FillSampleValues 10
    TChart1.Series(1).FillSampleValues 10
    
    'TChart1.Series(2).Active = False ' If you use a Subtract Function
End Sub

Private Sub TChart1_OnMouseMove(ByVal Shift As TeeChart.EShiftState, ByVal X As Long, ByVal Y As Long)
    For i = 0 To TChart1.SeriesCount - 2
        Index = TChart1.Series(i).Clicked(X, Y)
        
        If Index <> -1 Then
            TChart1.Header.Text.Clear
            'TChart1.Header.Text.Add CStr(TChart1.Series(2).YValues.Value(Index)) 'If you use a Subtract Function
            TChart1.Header.Text.Add CStr(TChart1.Series(1).YValues.Value(Index) - _
                                        TChart1.Series(0).YValues.Value(Index))
        End If
    Next
End Sub

[Aligator]

Thanks, this is not bad but the result is false if the pointer is between two points, the nearest point before is taken for the calculation.
Do you think there is a possibility to get the real values on each charts to do the same calculation ?
I must handle two records with different intervals on the same X date time. So, if we can get the displayed value for each record, it will be great and easy to do.
regards
JP

[Narcís]

Hi JP,

In that case you should interpolate series points as shown on this thread. Once you have retrieved series values you just need to make the difference as Edu showed you.

[Aligator]

Hi, this is fantastic !!!
it's exactly what I need.
Thanks for your help.
Next time I will try to search a little more into the Forum before I ask something.

JP