Re: [eigen] documentation

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Ok, so then let me ask you the questions directly.

I want to use eigen for containing matrices or arbitrary size
with coefficients in a template class which could be
a) float point like "float", "double" but also higher precision like
"quadmath" or "mpreal"
b) or a number type arithmetic like "mpq_class", "flintxx" or "int"
or some number field types.

I already have my own type with
template<typename T>
struct MyMatrix
  int nbRow;
  int nbCol;
  T *ListElt;
but it depends on copy operators all around (though I should be
able to use the move semantic). So I was wondering if I could
use eigen as a more advanced matrix operation container.

I have no problem using eigen in a single routine and computing
inverse, which are actually of better quality than the one I computed
with my own stupid Gauss elimination code. However, I have
problems with the copy operators and how to acess to the class

Q1: How to write a function that returns a matrix?
the following code does not compile:
Eigen::Matrix<double> HilbertMatrix(int const& n)
  Eigen::Matrix<double,Dynamic,Dynamic> eMat(n, n);
  for (int i=0; i<n; i++)
    for (int j=0; j<n; j++)
  return eMat;

Q2: What is the list of individual operations? I imagine
inverses function should be different between a floating
point type and an exact number theoretic type. How can
I acces exact inverse functions?

Q3: For the number theoretic operations, the technique
is to do Gauss rows and columns operations. I understand
Gauss elimination is out of consideration for floating
point operations. But for number theory this is what is
needed. Can we have access to operation like
 Ci <----- >Ci - a Cj ?

Q4: I sometimes need higher dimensional containers.
I wrote one inspired by "MyMatrix". Is there something
similar in Eigen? I guess no, just asking.

Q5: There are many examples of use eigen in the code
but they are all more or less of the same kind.
   a) Could we get examples that use template parameters?
double and float are fine but that is not what all there is
   b) Could we get examples with variable matrix size?
   c) Could we get use of copy constructors and assignment

Thank you very much in advance.


On Tue, Nov 18, 2014 at 9:53 PM, Gael Guennebaud <gael.guennebaud@xxxxxxxxx> wrote:

This looks like a doxygen bug, and we are not the first to encounter this issue:


On Tue, Nov 18, 2014 at 5:59 PM, Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On 16.11.2014 18:39, Mathieu Dutour wrote:
For example the following two lines are problematic:
because the corresponding .tex file does not exist.

I currently don't have the time to look into that problem. Could you add a bugzilla entry for that? (Also mention in that entry that GENERATE_LATEX shall be enabled/enable-able)

If you are able to fix the problem, a patch would be welcome, of course.


Dipl.-Inf., Dipl.-Math. Christoph Hertzberg
Cartesium 0.049
Universität Bremen
Enrique-Schmidt-Straße 5
28359 Bremen

Tel: +49 (421) 218-64252

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