-- File:	Extrema_GLocateExtPC.cdl
-- Created:	Tue Dec 14 16:24:56 1993
-- Author:	Christophe MARION
--		<cma@zerox>
---Copyright:	 Matra Datavision 1993


generic class  GLocateExtPC from Extrema(
    TheCurve          as any;
    TheCurveTool      as any;
    TheExtPElC        as any;
    ThePoint          as any;
    TheVector         as any;
    ThePOnC           as any;
    TheSequenceOfPOnC as any)

    	---Purpose: It calculates the distance between a point and a
    	--          curve with a close point.
    	--          This distance can be a minimum or a maximum.

uses CurveType      from GeomAbs


raises  DomainError from Standard,
        NotDone     from StdFail
	
    class ELPC    instantiates GExtPC      from Extrema
    	(TheCurve,
         TheCurveTool,
	 TheExtPElC,
         ThePoint,
         TheVector,
         ThePOnC,
         TheSequenceOfPOnC);


    class LocEPC  instantiates GenLocateExtPC      from Extrema
    	(TheCurve,
	 TheCurveTool,
         ThePOnC,
         ThePoint,
         TheVector);


is

    Create returns GLocateExtPC;

    Create (P: ThePoint; C: TheCurve; U0: Real; TolF: Real)
    	returns GLocateExtPC
    	---Purpose: Calculates the distance with a close point.
    	--          The close point is defined by the parameter value
    	--          U0.
    	--          The function F(u)=distance(P,C(u)) has an extremum
    	--          when g(u)=dF/du=0. The algorithm searchs a zero 
    	--          near the close point.
    	--          TolF is used to decide to stop the iterations.
    	--          At the nth iteration, the criteria is:
    	--           abs(Un - Un-1) < TolF.
    	raises  DomainError;
	    	-- if U0 is outside the definition range of the curve.


    Create (P: ThePoint; C: TheCurve; U0: Real; Umin, Usup: Real; TolF: Real)
    	returns GLocateExtPC
    	---Purpose: Calculates the distance with a close point.
    	--          The close point is defined by the parameter value
    	--          U0.
    	--          The function F(u)=distance(P,C(u)) has an extremum
    	--          when g(u)=dF/du=0. The algorithm searchs a zero 
    	--          near the close point.
    	--          Zeros are searched between Umin et Usup.
    	--          TolF is used to decide to stop the iterations.
    	--          At the nth iteration, the criteria is:
    	--           abs(Un - Un-1) < TolF.
    	raises  DomainError;
	    	-- if U0 is outside the definition range of the curve.

    Initialize(me: in out; C: TheCurve; Umin, Usup: Real; TolF: Real)
    	---Purpose: sets the fields of the algorithm.
    is static;


    Perform(me: in out; P: ThePoint; U0: Real)
	---Purpose: 

    is static;
    

    IsDone (me) returns Boolean
    	---Purpose: Returns True if the distance is found.
    	is static;

    SquareDistance (me) returns Real
    	---Purpose: Returns the value of the extremum square distance.
    	raises  NotDone from StdFail
	    	-- if IsDone(me)=False.
    	is static;

    IsMin (me) returns Boolean
    	---Purpose: Returns True if the extremum distance is a minimum.
    	raises  NotDone from StdFail
	    	-- if IsDone(me)=False.
    	is static;

    Point (me) returns ThePOnC
    	---Purpose: Returns the point of the extremum distance.
    	raises  NotDone from StdFail
	    	-- if IsDone(me)=False.
    	is static;


    
fields
    mypp:       ThePOnC;
    myC:        Address        from Standard;
    mydist2:     Real           from Standard;
    myismin:    Boolean        from Standard;
    myDone :    Boolean        from Standard;
    myumin:     Real           from Standard;
    myusup:     Real           from Standard;
    mytol:      Real           from Standard;
    myLocExtPC: LocEPC         from Extrema;
    myExtremPC: ELPC           from Extrema;
    type:       CurveType      from GeomAbs;
    numberext:  Integer        from Standard;

end GLocateExtPC;