I am using the cholesky decomposition LDLT in my code. I followed the tutorial at http://eigen.tuxfamily.org/dox/Tutorial ... gebra.html, the section of cholesky. If I define the decomposed matrices as:

Eigen::LLT<MatrixXd> ldlteigenrigid(eigenRigid);

The program runs. How should I run for LDLT? Whe I use

Eigen::LDLT<MatrixXd> EIRI;

I obtain a criptic error:

globalFEM.h:41: error: no matching function for call to 'Eigen::LDLT<Eigen::Matrix<double, 10000, 10000, 2, 10000, 10000> >::LDLT()'

How should I use it? Thanks,

Indeed, there is a little discrepancy in the API of Eigen 2.0: while LLT has a default constructor and allows you to compute the decomposition afterwards with compute(), this is not the case with LDLT. Instead you must pass the matrix to the constructor.

So:

Code: Select all

LDLT<MatrixXd> myLdlt(myMatrix);


Thanks for the answer, Jacob. Then my only solutions is to have the LDLT and the loop over the different vectors on the same function? As of now I had my code organized in such a way that one function created the LDLT object and another one calculated the loop over the different vectors.

Yes, unfortunately, with Eigen 2.0, that's your only solution ... But in the development branch (pre-3.0) there is a default constructor so you might consider using that. It is more powerful, tooo (it does pivoting).

-Benoit

Thanks Benoit,

I have troubles building the examples for eigen3. At the source:

gavox@NyarlHotep:~/software/eigen/demos$

I type cmake . and obtain:

-- Configuring done
-- Generating done
-- Build files have been written to: /home/gavox/software/eigen/demos

Now type make and got errors:

[ 12%] Building CXX object mandelbrot/CMakeFiles/mandelbrot.dir/mandelbrot.o
In file included from /home/gavox/software/eigen/demos/mandelbrot/mandelbrot.cpp:25:
/home/gavox/software/eigen/demos/mandelbrot/mandelbrot.h:28:23: error: Eigen/Array: No such file or directory
In file included from /home/gavox/software/eigen/demos/mandelbrot/mandelbrot.cpp:25:
/home/gavox/software/eigen/demos/mandelbrot/mandelbrot.h:54: error: 'Eigen' has not been declared
/home/gavox/software/eigen/demos/mandelbrot/mandelbrot.h:54: error: ISO C++ forbids declaration of 'Vector2d' with no type
/home/gavox/software/eigen/demos/mandelbrot/mandelbrot.h:54: error: expected ';' before 'center'
/home/gavox/software/eigen/demos/mandelbrot/mandelbrot.h: In constructor 'MandelbrotWidget::MandelbrotWidget()':
/home/gavox/software/eigen/demos/mandelbrot/mandelbrot.h:70: error: cl

and lot more. As if it would not find eigen. I did an install in /usr/local/include/eigen3/.

We haven't even tried building the demos in the devel branch in a loooonng time. We'll probably fix it just before the 3.0 release.