^{ICurveFittingFunction.FirstCalcPoint
ICurveFittingFunction}

<sup>property FirstCalcPoint: Integer;

Type Library
TeeChartx

Description
Default Value: -1</sup>

^{Sets the first point index used to calculate the fitting}

^{With FirstCalcPoint and LastcalcPoint properties you can restrict the subset of points CurveFittingFunction will use to calculate the polynomy coefficients and it's point values. Use FirstPoint and LastPoint to restrict the display range.}

^{By default is -1, meaning all datasource points from the beginning will be used to perform the calculation.}

^{The CheckDataSource method must be called after setting FirstPoint and LastPoint properties, forcing CurveFittingSeries to recalculate again all point values.}

^{Example [Visual Basic]:}

^{In this example FirstPoint is being used with FirstValueIndex / LastValueIndex to refit a fitted curve (CurveFitSeries1) to a 'zoomed' series (LineSeries1).}

^{Private Sub TChart1_OnZoom()}

^{With TChart1}

^{If .Series(0).FirstValueIndex > 0 Then}

^{.Series(1).FunctionType.asCurveFit.FirstCalcPoint = _}

^{.Series(0).FirstValueIndex - 1}

^{.Series(1).FunctionType.asCurveFit.LastCalcPoint = _}

^{.Series(0).LastValueIndex}

^Else

^{.Series(1).FunctionType.asCurveFit.FirstCalcPoint = _}

^{.Series(0).FirstValueIndex}

^{.Series(1).FunctionType.asCurveFit.LastCalcPoint = _}

^{.Series(0).LastValueIndex}

^{End If}

^{If .Series(0).LastValueIndex - .Series(0).FirstValueIndex > 6 Then}

^{.Series(1).FunctionType.asCurveFit.FirstPoint = _}

^{.Series(0).FirstValueIndex + 1}

^{.Series(1).FunctionType.asCurveFit.LastPoint = _}

^{.Series(0).LastValueIndex - 1}

^{End If}

^{.Series(0).CheckDataSource}

^{End With}

^{End Sub}