SundanceSymbolicFunc.hpp

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//                              Sundance
//                 Copyright (2005) Sandia Corporation
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#ifndef SUNDANCE_SYMBOLICFUNC_H
#define SUNDANCE_SYMBOLICFUNC_H


#include "SundanceDefs.hpp"
#include "SundanceListExpr.hpp"
#include "SundanceSymbolicFuncDescriptor.hpp"
#include "SundanceFunctionWithID.hpp"
#include "SundanceDiscreteFuncElement.hpp"
#include "SundanceDiscreteFunctionStub.hpp"

namespace Sundance
{
using namespace Sundance;
using namespace Teuchos;
    

/** 
 * SymbolicFunc is a base class for functions such as test and unknown
 * functions that are "variables" in a weak form. Symbolic functions
 * cannot be evaluated directly; before evaluating a weak form,
 a value must be substituted for 
 * each symbolic func using either the substituteZero() or
 * substituteFunction() method. 
 *
 * A symbolic function will construct itself as a list of
 * SymbolicFuncElement objects that point back to the SymbolicFunction.
 */
class SymbolicFunc : public ListExpr, public SymbolicFuncDescriptor,
  public FunctionWithID
{
public:
  /** Ctor records common data but initializes list to empty */
  SymbolicFunc(const FunctionWithID& fid, 
    const RCP<const CommonFuncDataStub>& data);

  /** virtual destructor */
  virtual ~SymbolicFunc() {;}

  /** Specify that expressions involving this function are to be evaluated
   * with this function set to zero. This is appropriate for computing
   * the functional derivatives that arise in a linear problem */
  void substituteZero() const ;

  /** Specify that expressions involving this function are to be evaluated
   * with this function set to the discrete function \f$u_0\f$. 
   * This is appropriate for computing
   * the functional derivatives that arise in a nonlinear expression
   * being linearized about \f$u_0\f$. 
   */
  void substituteFunction(const RCP<DiscreteFunctionStub>& u0) const ;

  /** */
  const RCP<const CommonFuncDataStub>& commonData() const 
    {return commonData_;}
  

private:
  RCP<const CommonFuncDataStub> commonData_;

};
}


#endif