Get any point's Coordinates in a Curve

[Schoumi]

hum ok, but in an interpolated curve, two points can be on each side of an extremum and obtain the extremum value could not be as easier as calculate a line equation between two point, because the result must not be on the curve, or i'm wrong again?

Thanks for your explanation

[FelixB]

Hi schuomi,

a QwtPlotCurve is not a "real" curve. It is a number of points that are connected by straight lines. So it is not possible that there is an extremum between two points.

If your curve uses interpolated data, you must access the "real" data storage to obtain the underlying values.

Felix