148 lines
3.9 KiB
C++
148 lines
3.9 KiB
C++
//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.4
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// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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//----------------------------------------------------------------------------
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://www.antigrain.com
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//----------------------------------------------------------------------------
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//
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// Solving simultaneous equations
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//
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//----------------------------------------------------------------------------
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#ifndef AGG_SIMUL_EQ_INCLUDED
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#define AGG_SIMUL_EQ_INCLUDED
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#include <cmath>
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#include "agg_basics.h"
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namespace agg
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{
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//=============================================================swap_arrays
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template<class T> void swap_arrays(T* a1, T* a2, unsigned n)
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{
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unsigned i;
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for(i = 0; i < n; i++)
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{
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T tmp = *a1;
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*a1++ = *a2;
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*a2++ = tmp;
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}
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}
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//============================================================matrix_pivot
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template<unsigned Rows, unsigned Cols>
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struct matrix_pivot
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{
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static int pivot(double m[Rows][Cols], unsigned row)
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{
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int k = int(row);
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double max_val, tmp;
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max_val = -1.0;
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unsigned i;
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for(i = row; i < Rows; i++)
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{
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if((tmp = std::fabs(m[i][row])) > max_val && tmp != 0.0)
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{
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max_val = tmp;
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k = i;
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}
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}
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if(m[k][row] == 0.0)
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{
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return -1;
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}
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if(k != int(row))
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{
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swap_arrays(m[k], m[row], Cols);
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return k;
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}
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return 0;
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}
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};
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//===============================================================simul_eq
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template<unsigned Size, unsigned RightCols>
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struct simul_eq
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{
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static bool solve(const double left[Size][Size],
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const double right[Size][RightCols],
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double result[Size][RightCols])
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{
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unsigned i, j, k;
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double a1;
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double tmp[Size][Size + RightCols];
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for(i = 0; i < Size; i++)
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{
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for(j = 0; j < Size; j++)
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{
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tmp[i][j] = left[i][j];
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}
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for(j = 0; j < RightCols; j++)
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{
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tmp[i][Size + j] = right[i][j];
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}
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}
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for(k = 0; k < Size; k++)
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{
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if(matrix_pivot<Size, Size + RightCols>::pivot(tmp, k) < 0)
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{
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return false; // Singularity....
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}
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a1 = tmp[k][k];
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for(j = k; j < Size + RightCols; j++)
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{
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tmp[k][j] /= a1;
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}
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for(i = k + 1; i < Size; i++)
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{
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a1 = tmp[i][k];
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for (j = k; j < Size + RightCols; j++)
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{
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tmp[i][j] -= a1 * tmp[k][j];
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}
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}
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}
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for(k = 0; k < RightCols; k++)
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{
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int m;
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for(m = int(Size - 1); m >= 0; m--)
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{
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result[m][k] = tmp[m][Size + k];
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for(j = m + 1; j < Size; j++)
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{
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result[m][k] -= tmp[m][j] * result[j][k];
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}
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}
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}
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return true;
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}
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};
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}
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#endif
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