GogSmoothedCurve
GogSmoothedCurve; GogSmoothedCurveClass;
GObject +----GogObject +----GogStyledObject +----GogTrendLine +----GogSmoothedCurve
GogSmoothedCurve implements GOStyledObject and GogDataset.
typedef struct _GogSmoothedCurve GogSmoothedCurve;
typedef struct { GogTrendLineClass base; int max_dim; } GogSmoothedCurveClass;