[eigen] lazy evaluation in sparse matrix multiply |

[ Thread Index |
Date Index
| More lists.tuxfamily.org/eigen Archives
]

Hi,

`in trying out some of the Eigen sparse-matrix functionality, I noticed,
``that unlike dense matrix multiplication, sparse matrices appear to
``default to lazy evaluation of matrix multiplication.
`
This causes an expression of the type
M = M * M;
to yield a zero matrix when used with sparse matrices.
Forced evaluation as in
M = (M * M).eval();
on the other hand, has the desired effect.

`I suggest setting the evaluate-before-assigning flag for sparse
``matrix-product expressions.
`
Regards
Frederik

`P.S.: What is the current status of complex Hermitian sparse (or block
``tridiagonal) eigenproblems in Eigen?
`