[eigen] Partially fixed size matrices.

[Tim Hutt <tdhutt@xxxxxxxxx>]

Hi,

One of the examples given in the documentation says that you can do
things like this:

Eigen::Matrix<double, Dynamic, 1> foo(10); // A 10x1 matrix (ie a vector)

However, it makes no mention of if you can do this:

Eigen::Matrix<double, Dynamic, 2> bar(???); // An Nx2 matrix.

And none of the constructors seem appropriate for a matrix like this.
The single argument one is the only one that really makes sense and it
says it is only for vectors. Also looking in the source code there are
several lines with things like

if (compile_time_columns == 1 ...

which makes me suspect that it only works for vectors. Either way the
documentation really needs to be clarified.

While on the topic of documentation it would be awesome if you could
set up a way to append comments to the documentation pages. This can
be very useful, e.g. the MySQL documentation has (or had, they seem to
have changed it a bit) a lot of useful comments.

Tim