Re: [ublas] symmetric matrices, row and column-major

Subject: Re: [ublas] symmetric matrices, row and column-major
From: Tiago Requeijo (tiago.requeijo.dev_at_[hidden])
Date: 2009-02-24 15:53:17

Here it is some code that should do the trick.  I tested it with boost 1.32,
1.37 and 1.38.  It fails on 1.37 and 1.38.

-----------------------------------------------------------------------------------------

#include <iostream>
#include <boost/numeric/ublas/symmetric.hpp>
using namespace std;
namespace ublas = boost::numeric::ublas;

int main(int argc, char* argv[])
{
    int sz = 4;
    ublas::symmetric_matrix<int, ublas::upper, ublas::column_major>  UpCol
(sz, sz);
    ublas::symmetric_matrix<int, ublas::upper, ublas::row_major>     UpRow
(sz, sz);
    ublas::symmetric_matrix<int, ublas::lower, ublas::column_major>  LoCol
(sz, sz);
    ublas::symmetric_matrix<int, ublas::lower, ublas::row_major>     LoRow
(sz, sz);

    for(int i=0; i<sz; ++i)
    {
        for(int j=i; j<sz; ++j)
        {
            UpCol(i,j) = 10*i + j;
            UpRow(i,j) = 10*i + j;
            LoCol(i,j) = 10*i + j;
            LoRow(i,j) = 10*i + j;
        }
    }

    //get pointers to data
    int* uc = &(UpCol.data()[0]);
    int* ur = &(UpRow.data()[0]);
    int* lc = &(LoCol.data()[0]);
    int* lr = &(LoRow.data()[0]);

    // upper, column_major
    //   storage should be:  0 1 11 2 12 22 3 13 23 33
    int uc_correct[] = {0, 1, 11, 2, 12, 22, 3, 13, 23, 33};

    // upper, row_major
    //   storage should be:  0 1 2 3 11 12 13 22 23 33
    int ur_correct[] = {0, 1, 2, 3, 11, 12, 13, 22, 23, 33};

    // lower, column_major
    //   storage should be:  0 1 2 3 11 12 13 22 23 33
    int lc_correct[] = {0, 1, 2, 3, 11, 12, 13, 22, 23, 33};

    // lower, row_major
    //   storage should be:  0 1 11 2 12 22 3 13 23 33
    int lr_correct[] = {0, 1, 11, 2, 12, 22, 3, 13, 23, 33};

    // Test
    for(int i=0; i<sz*(sz+1)/2; ++i)
        if(uc[i] != uc_correct[i])
        {
            cout << "Storage error (Upper, Column major)" << endl;
            break;
        }

    for(int i=0; i<sz*(sz+1)/2; ++i)
        if(ur[i] != ur_correct[i])
        {
            cout << "Storage error (Upper, Row major)" << endl;
            break;
        }

    for(int i=0; i<sz*(sz+1)/2; ++i)
        if(lc[i] != lc_correct[i])
        {
            cout << "Storage error (Lower, Column major)" << endl;
            break;
        }

    for(int i=0; i<sz*(sz+1)/2; ++i)
        if(lr[i] != lr_correct[i])
        {
            cout << "Storage error (Lower, Row major)" << endl;
            break;
        }

    return 0;
}

-----------------------------------------------------------------------------------------

On Tue, Feb 24, 2009 at 2:13 PM, Gunter Winkler <guwi17_at_[hidden]> wrote:

> Tiago Requeijo schrieb:
> > I'm having a problem with row and column major in symmetric matrices.
> > I'm probably not understanding correctly how the storage takes place
> > in memory.  I assumed upper+column_major storage was the same as
> > lower+row_major. Here's an example:
> >
> It would be very helpful if you could write a short example program that
> compares the actual storage with the expected one. I can add this
> program to the set of unit tests and fix the problem.
>
> mfg
> Gunter
>
> _______________________________________________
> ublas mailing list
> ublas_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/ublas
>