search

linbox-team / linbox

LinBox - C++ library for exact, high-performance linear algebra
https://linbox-team.github.io/linbox
GNU Lesser General Public License v2.1
83 stars 28 forks source link

Do not compute inverse for Blas Dixon #158

Open jgdumas opened 5 years ago

jgdumas commented 5 years ago

No need to compute the inverse mod p to lift in Dixon. The PLUQ factorization is sufficient to solve the system at each iteration.

ClementPernet commented 5 years ago

It may depend on the dimension/magnitude: although the overall arithmetic count is always in favor of the PLUQ variant, solving with a PLUQ at each iteration may be expensive: poorer cache behavious of the permutations and 2 trsv are less efficient than 1 fgemm (due to more modular reductions). Some benchmarking is required for a comparison.