Parallel performance of a symmetric eigensolver based on the invariant subspace decomposition approach

Discusses work in progress on a complete eigensolver based on the symmetric invariant subspace decomposition algorithm (SYISDA) for dense symmetric matrices. We describe a recently developed acceleration technique that substantially reduces the overall work required by this algorithm, and review the algorithmic highlights of a distributed-memory implementation of this approach. These include a fast matrix-matrix multiplication algorithm, a new approach to parallel band reduction and tridiagonalization, and a harness for coordinating the divide-and-conquer parallelism in the problem. We present performance results for the dominant kernel, dense matrix multiplication, as well as for the overall SYISDA implementation on the Intel Touchstone Delta and the Intel Paragon