| /*---------------------------------------------------------------------------*\ | |
| ========= | | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | |
| \\ / O peration | Website: https://openfoam.org | |
| \\ / A nd | Copyright (C) 2011-2018 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 | |
| Multi-dimensional renumbering used in the Numerical Recipes | |
| fft routine. This version is recursive, so works in n-d : | |
| determined by the length of array nn | |
| \*---------------------------------------------------------------------------*/ | |
| // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // | |
| void Foam::fftRenumberRecurse | |
| ( | |
| List<complex>& data, | |
| List<complex>& renumData, | |
| const labelList& nn, | |
| label nnprod, | |
| label ii, | |
| label l1, | |
| label l2 | |
| ) | |
| { | |
| if (ii == nn.size()) | |
| { | |
| // we've worked out the renumbering scheme. Now copy | |
| // the components across | |
| data[l1] = complex(renumData[l2].Re(),renumData[l2].Im()); | |
| } | |
| else | |
| { | |
| // do another level of folding. First work out the | |
| // multiplicative value of the index | |
| nnprod /= nn[ii]; | |
| label i_1(0); | |
| for (label i=0; i<nn[ii]; i++) | |
| { | |
| // now evaluate the indices (both from array 1 and to | |
| // array 2). These get multiplied by nnprod to (cumulatively) | |
| // find the real position in the list corresponding to | |
| // this set of indices. | |
| if (i<nn[ii]/2) | |
| { | |
| i_1 = i + nn[ii]/2; | |
| } | |
| else | |
| { | |
| i_1 = i - nn[ii]/2; | |
| } | |
| // go to the next level of recursion. | |
| fftRenumberRecurse | |
| ( | |
| data, | |
| renumData, | |
| nn, | |
| nnprod, | |
| ii+1, | |
| l1+i*nnprod, | |
| l2+i_1*nnprod | |
| ); | |
| } | |
| } | |
| } | |
| void Foam::fftRenumber | |
| ( | |
| List<complex>& data, | |
| const labelList& nn | |
| ) | |
| { | |
| List<complex> renumData(data); | |
| label nnprod(1); | |
| forAll(nn, i) | |
| { | |
| nnprod *= nn[i]; | |
| } | |
| label ii(0), l1(0), l2(0); | |
| fftRenumberRecurse | |
| ( | |
| data, | |
| renumData, | |
| nn, | |
| nnprod, | |
| ii, | |
| l1, | |
| l2 | |
| ); | |
| } | |
| // ************************************************************************* // | |