root/bdm/math/chmat.h @ 39

/*!
 * \file
 * \brief Matrices in decomposed forms (LDL', LU, UDU', etc).
 * \author Vaclav Smidl.
 *
 * -----------------------------------
 * BDM++ - C++ library for Bayesian Decision Making under Uncertainty
 *
 * Using IT++ for numerical operations
 * -----------------------------------
 */

#ifndef CHMAT_H
#define CHMAT_H

#include <itpp/itbase.h>
#include "libDC.h"

using namespace itpp;

/*! \brief Symmetric matrix stored in square root decomposition using upper cholesky

This matrix represent $A=Ch Ch'$ where only the upper triangle is stored;

*/
class chmat : public sqmat {
protected:
//! Upper triangle of the cholesky matrix
        mat Ch;
public:

        void opupdt ( const vec &v, double w );
        mat to_mat();
        void mult_sym ( const mat &C );
        void mult_sym ( const mat &C , chmat &U ) const;
        void mult_sym_t ( const mat &C );
        void mult_sym_t ( const mat &C, chmat &U ) const;
        double logdet() const;
        vec sqrt_mult ( const vec &v ) const;
        double qform ( const vec &v ) const;
        void clear();
        void add ( const chmat &A2, double w=1.0 ) {};
        //!Inversion in the same form, i.e. cholesky
        void inv ( chmat &Inv ) const   { ( Inv.Ch ) = itpp::inv ( Ch );}; //ltuinv is wrong?
        ;
//      void inv ( mat &Inv );

        //! Destructor for future use;
        virtual ~chmat() {};
        //! Default constructor
        chmat ( const int dim0 ) : sqmat ( dim0 ),Ch ( dim0,dim0 ) {};
        //! Default constructor
        chmat ( const vec &v) : sqmat ( v.length() ),Ch ( diag(sqrt(v)) ) {};
        //! Default constructor (m3k:cholform)
        chmat ( const mat &M ) : sqmat ( M.rows() ),Ch ( M.rows(),M.cols() ) {
                mat Q;
                it_assert_debug ( M.rows() ==M.cols(),"chmat:: input matrix must be square!" );
                Ch=chol ( M );
        };
        //! Access function
        mat & _Ch() {return Ch;}
        //! Access functions
        void setD ( const vec &nD ) {Ch=diag ( sqrt(nD) );}
        //! Access functions
        void setD ( const vec &nD, int i ) {for ( int j=i;j<nD.length();j++ ) {Ch( j,j ) =sqrt(nD ( j-i ));}} //Fixme can be more general

        //! Operators
        chmat& operator += ( const chmat &A2 );
        chmat& operator -= ( const chmat &A2 ) ;
};


//////// Operations:
//!mapping of add operation to operators
inline chmat& chmat::operator += ( const chmat &A2 )  {this->add ( A2 );return *this;}
//!mapping of negative add operation to operators
inline chmat& chmat::operator -= ( const chmat &A2 )  {this->add ( A2,-1.0 );return *this;}
#endif // CHMAT_H