| 1 | /* |
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| 2 | ----------------------------------------------------------------------------- |
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| 3 | This source file is part of OGRE |
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| 4 | (Object-oriented Graphics Rendering Engine) |
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| 5 | For the latest info, see http://www.ogre3d.org/ |
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| 6 | |
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| 7 | Copyright (c) 2006 Torus Knot Software Ltd |
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| 8 | Also see acknowledgements in Readme.html |
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| 9 | |
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| 10 | This program is free software; you can redistribute it and/or modify it under |
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| 11 | the terms of the GNU Lesser General Public License as published by the Free Software |
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| 12 | Foundation; either version 2 of the License, or (at your option) any later |
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| 13 | version. |
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| 14 | |
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| 15 | This program is distributed in the hope that it will be useful, but WITHOUT |
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| 16 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
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| 17 | FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. |
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| 18 | |
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| 19 | You should have received a copy of the GNU Lesser General Public License along with |
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| 20 | this program; if not, write to the Free Software Foundation, Inc., 59 Temple |
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| 21 | Place - Suite 330, Boston, MA 02111-1307, USA, or go to |
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| 22 | http://www.gnu.org/copyleft/lesser.txt. |
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| 23 | ----------------------------------------------------------------------------- |
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| 24 | */ |
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| 25 | |
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| 26 | #include "OgreStableHeaders.h" |
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| 27 | #include "OgreCommon.h" |
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| 28 | #include "OgreNumerics.h" |
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| 29 | |
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| 30 | |
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| 31 | namespace Ogre |
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| 32 | { |
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| 33 | bool NumericSolver::solveNxNLinearSysDestr(int n, PreciseReal **coeff, PreciseReal *col) |
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| 34 | { |
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| 35 | // we'll use standard row reduction; since we only care about systems with unique |
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| 36 | // solutions, our job is slightly easier. more can probably be done later to improve |
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| 37 | // precision versus this naive method |
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| 38 | |
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| 39 | int i, j; |
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| 40 | |
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| 41 | for(j=0; j<n; j++) |
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| 42 | { |
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| 43 | // look for a row with a leading coefficient we can use to cancel the rest |
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| 44 | int nonzeroIndex = -1; |
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| 45 | for(i=j; i<n; i++) { |
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| 46 | if (coeff[i][j] != 0.0) { |
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| 47 | nonzeroIndex = i; |
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| 48 | break; |
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| 49 | } |
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| 50 | } |
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| 51 | if (nonzeroIndex < 0) |
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| 52 | return false; |
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| 53 | PreciseReal *tptr = coeff[j]; |
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| 54 | coeff[j] = coeff[nonzeroIndex]; |
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| 55 | coeff[nonzeroIndex] = tptr; |
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| 56 | PreciseReal tval = col[j]; |
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| 57 | col[j] = col[nonzeroIndex]; |
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| 58 | col[nonzeroIndex] = tval; |
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| 59 | nonzeroIndex = j; |
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| 60 | |
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| 61 | // normalize row to have leading coeff of 1 and kill other rows' entries |
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| 62 | PreciseReal invelt = 1.0 / coeff[nonzeroIndex][j]; |
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| 63 | int k; |
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| 64 | for (k=j; k<n; k++) |
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| 65 | coeff[nonzeroIndex][k] *= invelt; |
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| 66 | col[nonzeroIndex] *= invelt; |
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| 67 | for (i=0; i<n; i++) { |
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| 68 | if (i==nonzeroIndex || coeff[i][j] == 0.0) |
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| 69 | continue; |
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| 70 | PreciseReal temp = coeff[i][j]; |
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| 71 | for (k=j; k<n; k++) |
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| 72 | coeff[i][k] -= temp * coeff[nonzeroIndex][k]; |
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| 73 | col[i] -= temp * col[nonzeroIndex]; |
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| 74 | } |
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| 75 | } |
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| 76 | |
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| 77 | return true; |
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| 78 | } |
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| 79 | |
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| 80 | } |
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