[Insight-users] vnl differences from VS2008 and command prompt

[John D]

Hi all,

  I am using some vnl calls and the results when I use the Visual Studio
2008 Debugger is different from the results if I run the program at the
command prompt. The iresults I get from the debugger seem to be the correct
one.

I am trying to decompose an affine matrix into its components and here is
the code:

     //Compute the rotation angle and scaling from SVD of the matrix.
        vnl_matrix<double> p(2, 2);
        p[0][0] = (double) vOutputParameters[0];
        p[0][1] = (double) vOutputParameters[1];
        p[1][0] = (double) vOutputParameters[2];
        p[1][1] = (double) vOutputParameters[3];
        vnl_svd<double> svd(p);
        vnl_matrix<double> r(2, 2);

        vnl_matrix<double> scalingDiag(2, 2);
        scalingDiag[0][0] = svd.W(0);
        scalingDiag[1][1] = svd.W(1);

        vnl_matrix<double> scalingMat(2, 2);
        scalingMat = svd.V()*scalingDiag*vnl_transpose(svd.V());

        vnl_matrix<double> rotationMat(2,2);
        rotationMat = svd.U()*vnl_transpose(svd.V());
        double angle    = -atan(rotationMat[0][1]/rotationMat[0][0]);
        double sinAngle = sin(angle);

        std::cout << "  Lambda1 :  = " << svd.W(0)<< std::endl;
        std::cout << "  Lambda2 :  = " << svd.W(1)<< std::endl;
        std::cout << "  V :  = " << svd.V()<< std::endl;
        std::cout << "  U :  = " << svd.U()<< std::endl;

        std::cout << " Scale 1         = " << scalingMat[0][0]
<< std::endl;
        std::cout << " Scale 2         = " << scalingMat[1][1]
<< std::endl;
        std::cout << " Angle (degrees) = " << angle * 45.0 / atan(1.0)
    << std::endl;
        std::cout << " Skew X          = " << scalingMat[0][1]
    << std::endl;
        std::cout << " Skew Y          = " << scalingMat[1][0]
    << std::endl;

scalingMat should be symmetric..which is the result I get from the debugger
(The code is compiled as release and the debugger is running from the same
directory which I use
to run from the commandline also)

For ex:
[ 0.99307       0.00623954;
  0.00623954  0.996727];

However from the command prompt, I get the following:
[0.992893    0.810226;
 -0.798249   0.996677];

Has anybody had problems like this before ? How can it be fixed?
Thanks,
John
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20100830/ee71170c/attachment.htm>