<a name="Intro"></a>
<h1>Introduction</h1>

<h3> About the example </h3>
This example shows how to combine iterative refinement with the adaptive
precision block-Jacobi preconditioner in order to approximately solve the
triangular systems occurring in ILU preconditioning. Using an adaptive precision
block-Jacobi preconditioner matrix as inner solver for the iterative refinement
method is equivalent to doing adaptive precision block-Jacobi relaxation in the
triangular solves. This example roughly approximates the triangular solves with
five adaptive precision block-Jacobi sweeps with a maximum block size of 16.

This example is motivated by "Multiprecision block-Jacobi for Iterative
Triangular Solves" (Göbel, Anzt, Cojean, Flegar, Quintana-Ortí, Euro-Par 2020).
The theory and a detailed analysis can be found there.
