Re: [eigen] Specialized QR

[ Thread Index | Date Index | More Archives ]

One more thing...
While your code is a great start for Givens-based QR, it is not what
we mean by "QR specialized for fixed-size". For example, the QR
currently in Eigen, when applied to a fixed-size matrix, specializes
exactly as well as your code to that case. But when we say that having
fixed-size specializations would be nice, we mean something else:
compilers tend to do a poor job unrolling nested for loops, so what we
really mean is that we'd need either hand-unrolled or meta-unrolled
code. For examples of meta-unrolled code, you can have a look at the
unrollers in Eigen/src/Core/Assign.h. For examples of hand-unrolled
specializations (moreover using custom algorithms depending on the
matrix size) have a look at Eigen/src/LU/Inverse.h. These are two
possible approaches. This is the kind of optimizations for fixed-size
that we had in mind when we said "fixed-size specializations of QR".


Mail converted by MHonArc 2.6.19+