// Created on: 1998-11-10
// Created by: Igor FEOKTISTOV
// Copyright (c) 1998-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _FEmTool_ElementsOfRefMatrix_HeaderFile
#define _FEmTool_ElementsOfRefMatrix_HeaderFile

#include "Standard.hxx"
#include "Standard_DefineAlloc.hxx"
#include "Standard_Handle.hxx"

#include "Standard_Integer.hxx"
#include "math_FunctionSet.hxx"
#include "math_Vector.hxx"
#include "PLib_HermitJacobi.hxx"

//! this class describes the functions needed for calculating
//! matrix elements of RefMatrix for linear criteriums
//! (Tension, Flexion and Jerk) by Gauss integration.
//! Each function from set gives value Pi(u)'*Pj(u)' or
//! Pi(u)''*Pj(u)'' or Pi(u)'''*Pj(u)''' for each i and j,
//! where Pi(u) is i-th basis function of expansion and
//! (') means derivative.
class FEmTool_ElementsOfRefMatrix : public math_FunctionSet
{
public:
  DEFINE_STANDARD_ALLOC

  Standard_EXPORT FEmTool_ElementsOfRefMatrix(const PLib_HermitJacobi& TheBase, const int DerOrder);

  //! returns the number of variables of the function.
  //! It is supposed that NbVariables = 1.
  Standard_EXPORT int NbVariables() const override;

  //! returns the number of equations of the function.
  Standard_EXPORT int NbEquations() const override;

  //! computes the values <F> of the functions for the
  //! variable <X>.
  //! returns True if the computation was done successfully,
  //! False otherwise.
  //! F contains results only for i<=j in following order:
  //! P0*P0, P0*P1, P0*P2... P1*P1, P1*P2,... (upper triangle of
  //! matrix {PiPj})
  Standard_EXPORT bool Value(const math_Vector& X, math_Vector& F) override;

private:
  PLib_HermitJacobi myBase;
  int               myDerOrder;
  int               myNbEquations;
};

#endif // _FEmTool_ElementsOfRefMatrix_HeaderFile