| /*---------------------------------------------------------------------------*\ | |
| ========= | | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | |
| \\ / O peration | Website: https://openfoam.org | |
| \\ / A nd | Copyright (C) 2011-2021 OpenFOAM Foundation | |
| \\/ M anipulation | | |
| ------------------------------------------------------------------------------- | |
| License | |
| This file is part of OpenFOAM. | |
| OpenFOAM is free software: you can redistribute it and/or modify it | |
| under the terms of the GNU General Public License as published by | |
| the Free Software Foundation, either version 3 of the License, or | |
| (at your option) any later version. | |
| OpenFOAM is distributed in the hope that it will be useful, but WITHOUT | |
| ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| for more details. | |
| You should have received a copy of the GNU General Public License | |
| along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>. | |
| Description | |
| The function renumbers the addressing such that the band of the | |
| matrix is reduced. The algorithm uses a simple search through the | |
| neighbour list | |
| See http://en.wikipedia.org/wiki/Cuthill-McKee_algorithm | |
| \*---------------------------------------------------------------------------*/ | |
| // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // | |
| Foam::labelList Foam::bandCompression(const labelListList& cellCellAddressing) | |
| { | |
| labelList newOrder(cellCellAddressing.size()); | |
| // the business bit of the renumbering | |
| SLList<label> nextCell; | |
| PackedBoolList visited(cellCellAddressing.size()); | |
| label cellInOrder = 0; | |
| // Work arrays. Kept outside of loop to minimise allocations. | |
| // - neighbour cells | |
| DynamicList<label> nbrs; | |
| // - corresponding weights | |
| DynamicList<label> weights; | |
| // - ordering | |
| labelList order; | |
| while (true) | |
| { | |
| // For a disconnected region find the lowest connected cell. | |
| label currentCell = -1; | |
| label minWeight = labelMax; | |
| forAll(visited, celli) | |
| { | |
| // find the lowest connected cell that has not been visited yet | |
| if (!visited[celli]) | |
| { | |
| if (cellCellAddressing[celli].size() < minWeight) | |
| { | |
| minWeight = cellCellAddressing[celli].size(); | |
| currentCell = celli; | |
| } | |
| } | |
| } | |
| if (currentCell == -1) | |
| { | |
| break; | |
| } | |
| // Starting from currentCell walk breadth-first | |
| // use this cell as a start | |
| nextCell.append(currentCell); | |
| // loop through the nextCell list. Add the first cell into the | |
| // cell order if it has not already been visited and ask for its | |
| // neighbours. If the neighbour in question has not been visited, | |
| // add it to the end of the nextCell list | |
| while (nextCell.size()) | |
| { | |
| currentCell = nextCell.removeHead(); | |
| if (!visited[currentCell]) | |
| { | |
| visited[currentCell] = 1; | |
| // add into cellOrder | |
| newOrder[cellInOrder] = currentCell; | |
| cellInOrder++; | |
| // find if the neighbours have been visited | |
| const labelList& neighbours = cellCellAddressing[currentCell]; | |
| // Add in increasing order of connectivity | |
| // 1. Count neighbours of unvisited neighbours | |
| nbrs.clear(); | |
| weights.clear(); | |
| forAll(neighbours, nI) | |
| { | |
| label nbr = neighbours[nI]; | |
| if (!visited[nbr]) | |
| { | |
| // not visited, add to the list | |
| nbrs.append(nbr); | |
| weights.append(cellCellAddressing[nbr].size()); | |
| } | |
| } | |
| // 2. Sort in ascending order | |
| sortedOrder(weights, order); | |
| // 3. Add in sorted order | |
| forAll(order, i) | |
| { | |
| nextCell.append(nbrs[i]); | |
| } | |
| } | |
| } | |
| } | |
| return newOrder; | |
| } | |
| Foam::labelList Foam::bandCompression | |
| ( | |
| const labelList& cellCells, | |
| const labelList& offsets | |
| ) | |
| { | |
| // Count number of neighbours | |
| labelList numNbrs(offsets.size()-1, 0); | |
| forAll(numNbrs, celli) | |
| { | |
| label start = offsets[celli]; | |
| label end = offsets[celli+1]; | |
| for (label facei = start; facei < end; facei++) | |
| { | |
| numNbrs[celli]++; | |
| numNbrs[cellCells[facei]]++; | |
| } | |
| } | |
| labelList newOrder(offsets.size()-1); | |
| // the business bit of the renumbering | |
| SLList<label> nextCell; | |
| PackedBoolList visited(offsets.size()-1); | |
| label cellInOrder = 0; | |
| // Work arrays. Kept outside of loop to minimise allocations. | |
| // - neighbour cells | |
| DynamicList<label> nbrs; | |
| // - corresponding weights | |
| DynamicList<label> weights; | |
| // - ordering | |
| labelList order; | |
| while (true) | |
| { | |
| // For a disconnected region find the lowest connected cell. | |
| label currentCell = -1; | |
| label minWeight = labelMax; | |
| forAll(visited, celli) | |
| { | |
| // find the lowest connected cell that has not been visited yet | |
| if (!visited[celli]) | |
| { | |
| if (numNbrs[celli] < minWeight) | |
| { | |
| minWeight = numNbrs[celli]; | |
| currentCell = celli; | |
| } | |
| } | |
| } | |
| if (currentCell == -1) | |
| { | |
| break; | |
| } | |
| // Starting from currentCell walk breadth-first | |
| // use this cell as a start | |
| nextCell.append(currentCell); | |
| // loop through the nextCell list. Add the first cell into the | |
| // cell order if it has not already been visited and ask for its | |
| // neighbours. If the neighbour in question has not been visited, | |
| // add it to the end of the nextCell list | |
| while (nextCell.size()) | |
| { | |
| currentCell = nextCell.removeHead(); | |
| if (!visited[currentCell]) | |
| { | |
| visited[currentCell] = 1; | |
| // add into cellOrder | |
| newOrder[cellInOrder] = currentCell; | |
| cellInOrder++; | |
| // Add in increasing order of connectivity | |
| // 1. Count neighbours of unvisited neighbours | |
| nbrs.clear(); | |
| weights.clear(); | |
| label start = offsets[currentCell]; | |
| label end = offsets[currentCell+1]; | |
| for (label facei = start; facei < end; facei++) | |
| { | |
| label nbr = cellCells[facei]; | |
| if (!visited[nbr]) | |
| { | |
| // not visited, add to the list | |
| nbrs.append(nbr); | |
| weights.append(numNbrs[nbr]); | |
| } | |
| } | |
| // 2. Sort in ascending order | |
| sortedOrder(weights, order); | |
| // 3. Add in sorted order | |
| forAll(order, i) | |
| { | |
| nextCell.append(nbrs[i]); | |
| } | |
| } | |
| } | |
| } | |
| return newOrder; | |
| } | |
| // ************************************************************************* // | |