-- File:	Difference.cdl
-- Created:	Mon Jan 14 16:20:15 1991
-- Author:	Arnaud BOUZY
--		<adn@topsn3>
---Copyright:	 Matra Datavision 1991

class Difference from Expr

inherits BinaryExpression from Expr

uses GeneralExpression from Expr,
    AsciiString from TCollection,
    Array1OfNamedUnknown from Expr,
    Array1OfReal from TColStd,
    NamedUnknown from Expr
    
raises OutOfRange from Standard, 
    NumericError from Standard,
    NotEvaluable from Expr

is

    Create(exp1,exp2 : GeneralExpression)
    ---Purpose: Creates the difference <exp1> - <exp2>.
    returns mutable Difference;

    ShallowSimplified(me) 
    ---Purpose: Returns a GeneralExpression after a simplification 
    --          of the arguments of <me>.
    returns any GeneralExpression
    raises NumericError;

    Copy(me)
    ---Purpose: Returns a copy of <me> having the same unknowns and functions.
    returns mutable like me;
    
    IsIdentical(me; Other : GeneralExpression)
    ---Purpose: Tests if <me> and <Other> define the same expression.
    --          This method does not include any simplification before
    --          testing.
    returns Boolean;

    IsLinear(me)
    returns Boolean;

    Derivative(me; X : NamedUnknown)
    ---Purpose: Returns the derivative on <X> unknown of <me> 
    returns any GeneralExpression;

    NDerivative(me; X : NamedUnknown; N : Integer)
    ---Purpose: Returns the <N>-th derivative on <X> unknown of <me>.
    --          Raises OutOfRange if <N> <= 0
    returns any GeneralExpression
    raises OutOfRange
    is redefined;

    Evaluate(me; vars : Array1OfNamedUnknown; vals : Array1OfReal)
    ---Purpose: Returns the value of <me> (as a Real) by 
    --          replacement of <vars> by <vals>.
    --          Raises NotEvaluable if <me> contains NamedUnknown not 
    --          in <vars> or NumericError if result cannot be computed.
    returns Real
    raises NotEvaluable,NumericError;

    String(me)
    ---Purpose: returns a string representing <me> in a readable way.
    returns AsciiString;

end Difference;