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| static void  | CalculateD0 (gp_Pnt2d &theValue, const gp_Vec2d &theD1, const Standard_Real theOffset) | 
|   | Recalculate D1 values of base curve into D0 value of offset curve.  
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| static void  | CalculateD1 (gp_Pnt2d &theValue, gp_Vec2d &theD1, const gp_Vec2d &theD2, const Standard_Real theOffset) | 
|   | Recalculate D2 values of base curve into D1 values of offset curve.  
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| static void  | CalculateD2 (gp_Pnt2d &theValue, gp_Vec2d &theD1, gp_Vec2d &theD2, const gp_Vec2d &theD3, const Standard_Boolean theIsDirChange, const Standard_Real theOffset) | 
|   | Recalculate D3 values of base curve into D2 values of offset curve.  
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| static void  | CalculateD3 (gp_Pnt2d &theValue, gp_Vec2d &theD1, gp_Vec2d &theD2, gp_Vec2d &theD3, const gp_Vec2d &theD4, const Standard_Boolean theIsDirChange, const Standard_Real theOffset) | 
|   | Recalculate D3 values of base curve into D3 values of offset curve.  
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| static Standard_Boolean  | AdjustDerivative (const Standard_Integer theMaxDerivative, const Standard_Real theU, gp_Vec2d &theD1, gp_Vec2d &theD2, gp_Vec2d &theD3, gp_Vec2d &theD4) | 
|   | Recalculate derivatives in the singular point Returns true if the direction of derivatives is changed.  
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The Geom2dEvaluator package provides utilities for . calculating value and derivatives of offset curve using corresponding values of base curve.