private static void TestSystemSolution(/*LinearAlgebraProviderChoice providers*/)
        {
            //TestSettings.RunMultiproviderTest(providers, delegate () {
            //

            var skyline = SkylineMatrix.CreateFromArrays(SparsePosDef10by10.Order, SparsePosDef10by10.SkylineValues,
                                                         SparsePosDef10by10.SkylineDiagOffsets, true, true);
            var        b         = Vector.CreateFromArray(SparsePosDef10by10.Rhs);
            var        xExpected = Vector.CreateFromArray(SparsePosDef10by10.Lhs);
            LdlSkyline factor    = skyline.FactorLdl(false);
            Vector     xComputed = factor.SolveLinearSystem(b);

            comparer.AssertEqual(xExpected, xComputed);

            //});
        }
 public Vector MultiplyInverseCoarseProblemMatrixTimes(Vector vector) => inverseGlobalKccStar.SolveLinearSystem(vector);