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// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.1 (2010/10/01)
#include "Wm5MathematicsPCH.h"
#include "Wm5ApprCircleFit2.h"
#include "Wm5ApprQuadraticFit2.h"
namespace Wm5
{
//----------------------------------------------------------------------------
template <typename Real>
bool CircleFit2 (int numPoints, const Vector2<Real>* points,
int maxIterations, Circle2<Real>& circle, bool initialCenterIsAverage)
{
// Compute the average of the data points.
Vector2<Real> average = points[0];
int i0;
for (i0 = 1; i0 < numPoints; ++i0)
{
average += points[i0];
}
Real invNumPoints = ((Real)1)/(Real)numPoints;
average *= invNumPoints;
// The initial guess for the center.
if (initialCenterIsAverage)
{
circle.Center = average;
}
else
{
QuadraticCircleFit2<Real>(numPoints, points, circle.Center,
circle.Radius);
}
int i1;
for (i1 = 0; i1 < maxIterations; ++i1)
{
// Update the iterates.
Vector2<Real> current = circle.Center;
// Compute average L, dL/da, dL/db.
Real lenAverage = (Real)0;
Vector2<Real> derLenAverage = Vector2<Real>::ZERO;
for (i0 = 0; i0 < numPoints; ++i0)
{
Vector2<Real> diff = points[i0] - circle.Center;
Real length = diff.Length();
if (length > Math<Real>::ZERO_TOLERANCE)
{
lenAverage += length;
Real invLength = ((Real)1)/length;
derLenAverage -= invLength*diff;
}
}
lenAverage *= invNumPoints;
derLenAverage *= invNumPoints;
circle.Center = average + lenAverage*derLenAverage;
circle.Radius = lenAverage;
Vector2<Real> diff = circle.Center - current;
if (Math<Real>::FAbs(diff[0]) <= Math<Real>::ZERO_TOLERANCE
&& Math<Real>::FAbs(diff[1]) <= Math<Real>::ZERO_TOLERANCE)
{
break;
}
}
return i1 < maxIterations;
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// Explicit instantiation.
//----------------------------------------------------------------------------
template WM5_MATHEMATICS_ITEM
bool CircleFit2<float> (int, const Vector2<float>*, int, Circle2<float>&,
bool);
template WM5_MATHEMATICS_ITEM
bool CircleFit2<double> (int, const Vector2<double>*, int, Circle2<double>&,
bool);
//----------------------------------------------------------------------------
}
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