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SubSMat.h

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/*
    File:           SubSMat.h

    Function:       Defines a scatter-gather sparse matrix, i.e., a submatrix of another sparse 
                    matrix.
                    
    Author(s):      Andrew Willmott

    Copyright:      (c) 1995-2000, Andrew Willmott
 */


#ifndef __SubSMat__
#define __SubSMat__

#include "vl/VL.h"
#include "vl/Mat.h"


// --- SubSMat Class ----------------------------------------------------------


class TSubSVec;
class TSparseVec;
class TSparseMat;

class TSubSMat
{
public:
    
    // Constructors
    
    TSubSMat(Int m, Int n, Int start, TMSparseVec *target);
    TSubSMat(const TSubSMat &m);            
    
    // Accessor functions
    
    inline Int              Rows() const { return rows; };
    inline Int              Cols() const { return cols; };

    inline TMSubSVec        operator [] (Int i) const;        

    // Assignment operators
    
    TSubSMat                &operator = (const TSubSMat &m);
    TSubSMat                &operator = (const TSparseMat &m);  
    TSubSMat                &operator = (const TMat &m);    

protected:

    Int                     rows;
    Int                     cols;
    Int                     start;
    TMSparseVec             *target; 
};

TMSubSVec   col(const TSparseMat &m, Int i);
TMSubSVec   diag(const TSparseMat &m, Int diagNum);
                    //  -i = diag. starting on row i, +i = diag. starting on col i
TSubSMat    sub(const TSparseMat &m, Int top, Int left, Int nrows, Int ncols);
TSubSMat    sub(const TSparseMat &m, Int nrows, Int ncols);


// --- SubSMat Inlines --------------------------------------------------------

#include "vl/SubSVec.h"
#include "vl/SparseVec.h"

inline TMSubSVec TSubSMat::operator [] (Int i) const
{
    Assert(i >= 0 && i < Rows(), "(SubSMat::[]) index out of range");
    return(sub(target[i], start, Cols()));
}

#endif

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