This is a dependency property.
'Declaration Public Function Stiffness( _ ByVal stiffness As System.Double _ ) As PolarSplineSeries(Of T)
public PolarSplineSeries<T> Stiffness( System.double stiffness )
Target Platforms: Windows 8.1, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
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