#ifndef NUMMODELLEASTSQUAREB_HH
#define NUMMODELLEASTSQUAREB_HH
////////////////////////////////////////////////////////////////////////////
//! author="Robert Crida"
//! lib=NumModelBasicModels
//! date="2/2/1998"
//! userlevel=Develop
//! file="amma/PatternRec/FuncTools/Model/BasicModels/NumModelLeastSquareB.hh"
//! docentry="Numerical Methods.Multidimensional Models.Implementation"
//! rcsid="$Id: NumModelLeastSquareB.hh,v 1.6 2000/02/16 14:10:26 ees1cg Exp $"

#include "amma/Num/NumModelB.hh"

// --------------------------------------------------------------------------
// **********  NumModelLeastSquareBC  ***************************************
// -------------------------------------------------------------------------
//: Least squares model fitting implementation class.
//
// It provides an implementation for performing model to data fitting using
// least squares regression. The form of the model is not incorporated in
// this class.<p>
//
// In order to actually create a new form of model it is necessary to
// overload the private member functions, MakeInput() and MakeJacobianInput().
// MakeInput must produce a vector which when multiplied by a matrix of the
// model weights will produce a prediction. Similarly, MakeJacobian() should
// produce a vector which when multiplied by the model weights produces the
// partial derivative vector corresponding to the parameter i.

class NumModelLeastSquareBC: public NumModelBC
{
  MatrixC _A;
  virtual VectorC MakeInput (const VectorC &X) const=0;
  //: Used for fitting and evaluating any linear model
  // The output of the model is determined as A*MakeInput(X) which is a matrix
  // multiplied by a vector.

  virtual VectorC MakeJacobianInput (const VectorC &X, IndexT i) const=0;
  //: Used for calculating Jacobian of linear model
  // Each column i of the Jacobian is determined as A*MakeJacobianInput(X,i)

public:
  NumModelLeastSquareBC (const StringC &name);
  //: Constructor takes concrete class name, this class is abstract

  NumModelLeastSquareBC (const StringC &name, istream &in);
  //: Constructor from a stream

  NumModelLeastSquareBC (const NumModelLeastSquareBC &m);
  //: Copy constructor

protected:
  virtual VectorC Evaluate (const VectorC &X) const;
  //: Evaluates Y=f(X)

  virtual void Fit (const NumVVDataSetC &train);
  //: Performs necessary model fitting to supplied training samples

  virtual MatrixC Jacobian (const VectorC &X) const;
  //: Evaluates Jacobian matrix df(X)/dX.

  virtual const StringC GetInfo () const;
  //: Prints information about the model

  virtual BooleanT Save (ostream &out) const;
  //: Saves the model to a stream
};

BooleanT IsMarginal (MatrixC m, SArray1dC<int> invalid);
//: Tests whether matrix is singular.
// IsMarginal is used to determine whether or not the matrix m is singular 
// and would therefore be impossible to invert. It is used by
// LeastSquaresModelC to detemine which parameters or model weights to
// incorporate.


#endif