Matrix repr assumes row major memory (eigen is column major)

[Jeff Packer]

The problem is just that repr goes through the elements in the incorrect order to print. This may have been intentional, but is inconsistent with the way Eiegen works.

C++ Example:

Eigen::Matrix4f m;
m << 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16;
Eigen::Matrix4f n = Eigen::Matrix4f::Ones();
cout << m * n << endl;

Output:

10 10 10 10
26 26 26 26
42 42 42 42
58 58 58 58

PyEigen Example:

>>> from pyeigen import *
>>> m = Matrix4f( 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16)
>>> m
Matrix4f(1.000000, 5.000000, 9.000000, 13.000000,
         2.000000, 6.000000, 10.000000, 14.000000,
         3.000000, 7.000000, 11.000000, 15.000000,
         4.000000, 8.000000, 12.000000, 16.000000)
>>> n = Matrix4f.ones()
>>> n
Matrix4f(1.000000, 1.000000, 1.000000, 1.000000,
         1.000000, 1.000000, 1.000000, 1.000000,
         1.000000, 1.000000, 1.000000, 1.000000,
         1.000000, 1.000000, 1.000000, 1.000000)
>>> m*n
Matrix4f(10.000000, 26.000000, 42.000000, 58.000000,
         10.000000, 26.000000, 42.000000, 58.000000,
         10.000000, 26.000000, 42.000000, 58.000000,
         10.000000, 26.000000, 42.000000, 58.000000)