74 lines
2.1 KiB
C++
74 lines
2.1 KiB
C++
// Geometric Tools, LLC
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// Copyright (c) 1998-2010
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// Distributed under the Boost Software License, Version 1.0.
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// http://www.boost.org/LICENSE_1_0.txt
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// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
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//
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// File Version: 4.10.0 (2009/11/18)
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#include "Wm4FoundationPCH.h"
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#include "Wm4ApprGaussPointsFit2.h"
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#include "Wm4Eigen.h"
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namespace Wm4
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{
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//----------------------------------------------------------------------------
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template <class Real>
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Box2<Real> GaussPointsFit2 (int iQuantity, const Vector2<Real>* akPoint)
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{
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Box2<Real> kBox(Vector2<Real>::ZERO,Vector2<Real>::UNIT_X,
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Vector2<Real>::UNIT_Y,(Real)1.0,(Real)1.0);
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// compute the mean of the points
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kBox.Center = akPoint[0];
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int i;
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for (i = 1; i < iQuantity; i++)
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{
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kBox.Center += akPoint[i];
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}
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Real fInvQuantity = ((Real)1.0)/iQuantity;
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kBox.Center *= fInvQuantity;
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// compute the covariance matrix of the points
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Real fSumXX = (Real)0.0, fSumXY = (Real)0.0, fSumYY = (Real)0.0;
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for (i = 0; i < iQuantity; i++)
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{
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Vector2<Real> kDiff = akPoint[i] - kBox.Center;
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fSumXX += kDiff.X()*kDiff.X();
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fSumXY += kDiff.X()*kDiff.Y();
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fSumYY += kDiff.Y()*kDiff.Y();
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}
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fSumXX *= fInvQuantity;
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fSumXY *= fInvQuantity;
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fSumYY *= fInvQuantity;
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// setup the eigensolver
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Eigen<Real> kES(2);
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kES(0,0) = fSumXX;
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kES(0,1) = fSumXY;
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kES(1,0) = fSumXY;
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kES(1,1) = fSumYY;
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kES.IncrSortEigenStuff2();
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for (i = 0; i < 2; i++)
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{
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kBox.Extent[i] = kES.GetEigenvalue(i);
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kES.GetEigenvector(i,kBox.Axis[i]);
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}
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return kBox;
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}
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//----------------------------------------------------------------------------
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//----------------------------------------------------------------------------
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// explicit instantiation
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//----------------------------------------------------------------------------
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template WM4_FOUNDATION_ITEM
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Box2<float> GaussPointsFit2<float> (int, const Vector2<float>*);
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template WM4_FOUNDATION_ITEM
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Box2<double> GaussPointsFit2<double> (int, const Vector2<double>*);
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//----------------------------------------------------------------------------
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}
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