CATLineFit.h

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/// \file CATLineFit.h
/// \brief Regression to fit a line to a set of points.
/// \ingroup CAT
///
/// Copyright (c) 2002-2008 by Michael Ellison.
/// See COPYING.txt for the \ref gaslicense License (MIT License).
///
// $Author: mikeellison $
// $Date: 2008-01-19 19:19:35 -0600 (Sat, 19 Jan 2008) $
// $Revision:   $
// $NoKeywords: $
#ifndef _CATLineFit_H_
#define _CATLineFit_H_

#include "CATInternal.h"
#include "CATPoint.h"
#include "CATMatrix.h"


/// \class CATLineFit
/// \brief Regression to fit a line to a set of points.
/// \ingroup CAT
class CATLineFit
{
    public:     
        CATLineFit();
        virtual ~CATLineFit();

        /// Add a point to the interpolation data
        bool        AddPoint( CATFloat64 x, CATFloat64 y);

        /// Clear out all current data
        bool        Clear();
        
        /// Get the number of data points acquired
        CATUInt32   GetNumPoints();

        /// Get an individual data point
        bool        GetDataPoint( CATUInt32 n, CATFloat64& x, CATFloat64& y);
        
        /// Calculate the Y val from a specified x val
        bool        CalcYVal( CATFloat64 x, CATFloat64& y);

        /// Get error value
        bool        GetCurrentErr( CATFloat64& err);

        /// Get min/max values for x and y
        bool        GetMinMax( CATFloat64& minX, CATFloat64& minY, CATFloat64& maxX, CATFloat64& maxY);

        /// Get the slope of the line 
        bool        Slope(CATFloat64& slope);

        /// Get the intercept of the line 
        bool        Intercept(CATFloat64& intercept);
    protected:      
        /// Internal calculation
        bool        CalcFit();  
        
        std::vector<CATPoint> fPointList;   ///< list of X points       
        CATFloat64            fLastErr;     ///< last calculated err

        CATUInt32   fDegree;        ///< Degree of coefficient to calculate with fit        
        bool        fDirty;         ///< Are the coefficients dirty? (i.e. need to call CalcFit?)
        CATFloat64  fSlope;         ///< If not dirty, this is the slope of the line
        CATFloat64  fIntercept;     ///< If not dirty, this is the intercept of the line
        CATFloat64  fSumX;          ///< The sum of all X values
        CATFloat64  fSumY;          ///< The sum of all Y values
        CATFloat64  fSumXY;         ///< The sum of all X values times their Y values
        CATFloat64  fSumXSquared;   ///< The sum of all X^2  (e.g. X1^2 + X2^2 .... + Xn^2)
};

#endif // _CATLineFit_H_

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