private static void TestReordering() { Skip.IfNot(TestSettings.TestSuiteSparse, TestSettings.MessageWhenSkippingSuiteSparse); int order = SparseSymm5by5.Order; int[] rowIndices = SparseSymm5by5.CscRowIndices; int[] colOffsets = SparseSymm5by5.CscColOffsets; int[] permutation = new int[order]; IntPtr common = SuiteSparsePInvokes.CreateCommon(0, 0); int status = SuiteSparsePInvokes.ReorderAMDUpper(order, rowIndices.Length, rowIndices, colOffsets, permutation, out int factorNNZ, common); Assert.True(status == 1, "SuiteSparse reordering failed. A possible reason is the lack of enough available memory"); comparer.AssertEqual(SparseSymm5by5.MatlabPermutationAMD, permutation); SuiteSparsePInvokes.DestroyCommon(ref common); }
/// <summary> /// Find a fill reducing permutation for the sparsity pattern of a symmetric matrix defined by the parameters. /// The returned permutation is new-to-old, namely reordered[i] = original[permutation[i]]. /// </summary> /// <param name="order">The number of rows/columns of the symmetric matrix.</param> /// <param name="nonZerosUpper">The number of (structural) non-zero entries in the upper triangle of the symmetric /// matrix.</param> /// <param name="cscRowIndices">Row indices of the upper triangle entries of the symmetric matrix, in Compressed Sparse /// Columns format. All row indices of the same column must be sorted.</param> /// <param name="cscColOffsets">Column offsets of the upper triangle entries of the symmetric matrix, in Compressed /// Sparse Columns format. All column offsets must be sorted.</param> /// <returns>permutation: An array containing the new-to-old fill reducing permutation. /// stats: Measuments taken by SuiteSparse during the execution of AMD.</returns> /// <exception cref="SuiteSparseException">Thrown if SuiteSparse dlls cannot be loaded or if AMD fails.</exception> public (int[] permutation, ReorderingStatistics stats) FindPermutation(int order, int nonZerosUpper, int[] cscRowIndices, int[] cscColOffsets) { var permutation = new int[order]; IntPtr common = SuiteSparsePInvokes.CreateCommon(0, 0); if (common == IntPtr.Zero) { throw new SuiteSparseException("Failed to initialize SuiteSparse."); } int status = SuiteSparsePInvokes.ReorderAMDUpper(order, nonZerosUpper, cscRowIndices, cscColOffsets, permutation, out int nnzFactor, common); if (status == 0) { throw new SuiteSparseException("AMD failed. This could be caused by the matrix being so large it" + " cannot be processed with the available memory."); } SuiteSparsePInvokes.DestroyCommon(ref common); return(permutation, new ReorderingStatistics(nnzFactor, -1)); }