Re: compressed2D insertion

Burkhard

I think you should use block-wise insertion (see http://www.osl.iu.edu/rese=
arch/mtl/mtl4/doc/matrix_insertion.html ). This is much faster.
Nevertheless since you are reading your matrix data from a file you will ne=
ed to think about how to block it first.

Regards,
Elmar
 =




-----Original Message-----
From: [email protected] [mailto:[email protected]] On=
 Behalf Of Burkhard M=F6ller
Sent: 16 October 2009 11:52
To: [email protected]
Subject: MTL: compressed2D insertion

Hi there,

I have an adjacency matrix of about 30000x30000 with ~200000 nonzero =

entries and I would like to use it with MTL. The matrix is in a file in =

matrix market format and I have slightly modified the first Matrix =

Insertion example to read it. The insertion of the first 100 elements =

already takes over 15 sec time, what am I doing wrong? I am using Visual =

Studio 2008 Express.

The source code is as follows:

// File: insert.cpp

#include <iostream>
#include <boost/numeric/mtl/mtl.hpp>

using namespace mtl;

template <typename Matrix>
void insval(Matrix& m, int index1, int index2, double val)
{
    // Matrices are not initialized by default
    m=3D 0.0;

    // Create inserter for matrix m
    matrix::inserter<Matrix> ins(m);
    =

    // Insert value
    ins[index1][index2] << val;

}



int main(int argc, char* argv[])
{
    compressed2D<double>              A(30000, 30000);
    =

    FILE* matrixfile;

    matrixfile=3Dfopen("A_cpp.txt","r");

    int count=3D0, index1=3D0, index2=3D0;
    double value=3D0;

    clock_t start, finish;
    double duration;

    start =3D clock();

    while(fscanf(matrixfile, "%d %d %Lg", &index1, &index2, &value)!=3DEOF =

&& count<100){// insert first 100 values only
        count++;
        insval(A, index1-40360, index2-40360, value); // smallest index =

is 40360...
    }

    finish =3D clock();

    duration =3D (double)(finish - start) / CLOCKS_PER_SEC;
    printf( "%2.1f seconds\n", duration );

    return 0;
}


Thanks for your time!

Rechnan
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