vnl_qr.h

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#ifndef vnl_qr_h_
#define vnl_qr_h_

//:
//  \file
//  \brief Calculate inverse of a matrix using QR
//  \author  Andrew W. Fitzgibbon, Oxford RRG, 08 Dec 96
//
//  Modifications:
//  081296 AWF Temporarily abandoned as I realized my problem was symmetric...
//  080697 AWF Recovered, implemented solve().
//  200897 AWF Added determinant().
//  071097 AWF Added Q(), R().
//  Christian Stoecklin, ETH Zurich, added QtB(v);
//  31-mar-2000 fsm@robots.ox.ac.uk: templated
//  dac (Manchester) 28/03/2001: tidied up documentation

#include <vnl/vnl_vector.h>
#include <vnl/vnl_matrix.h>

//: Calculate QR decomposition of a matrix.
//  More detailed description not available

export template <class T>
class vnl_qr {
public:
  vnl_qr(vnl_matrix<T> const & M);
 ~vnl_qr();
  
  vnl_matrix<T> inverse () const;   // inverse
  vnl_matrix<T> tinverse () const;  // transpose-inverse
  vnl_matrix<T> recompose () const;

  vnl_matrix<T> solve (const vnl_matrix<T>& rhs) const;
  vnl_vector<T> solve (const vnl_vector<T>& rhs) const;

  T determinant() const;
  vnl_matrix<T>& Q();
  vnl_matrix<T>& R();
  vnl_vector<T> QtB(const vnl_vector<T>& b) const;
  
  void extract_q_and_r(vnl_matrix<T>* Q, vnl_matrix<T>* R);

private:
  vnl_matrix<T> qrdc_out_;
  vnl_vector<T> qraux_;
  vnl_vector<int> jpvt_;
  vnl_matrix<T>* Q_;
  vnl_matrix<T>* R_;
  
  // Disallow assignment until I decide whether it's a good idea
  vnl_qr(const vnl_qr<T> &) { }
  void operator=(const vnl_qr<T> &) { }
};

//: Compute determinant of matrix "M" using QR.
template <class T>
inline T vnl_qr_determinant(vnl_matrix<T> const& m)
{
  return vnl_qr<T>(m).determinant();
}

export template <class T>
vcl_ostream& operator<<(vcl_ostream&, vnl_qr<T> const & qr);

#endif // vnl_qr_h_

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