/usr/include/tesseract/linlsq.h is in libtesseract-dev 3.02.01-6.
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* File: linlsq.h (Formerly llsq.h)
* Description: Linear Least squares fitting code.
* Author: Ray Smith
* Created: Thu Sep 12 08:44:51 BST 1991
*
* (C) Copyright 1991, Hewlett-Packard Ltd.
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
** http://www.apache.org/licenses/LICENSE-2.0
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*
**********************************************************************/
#ifndef TESSERACT_CCSTRUCT_LINLSQ_H_
#define TESSERACT_CCSTRUCT_LINLSQ_H_
#include "points.h"
#include "params.h"
class LLSQ {
public:
LLSQ() { // constructor
clear(); // set to zeros
}
void clear(); // initialize
// Adds an element with a weight of 1.
void add(double x, double y);
// Adds an element with a specified weight.
void add(double x, double y, double weight);
// Adds a whole LLSQ.
void add(const LLSQ& other);
// Deletes an element with a weight of 1.
void remove(double x, double y);
inT32 count() const { // no of elements
return static_cast<int>(total_weight + 0.5);
}
double m() const; // get gradient
double c(double m) const; // get constant
double rms(double m, double c) const; // get error
double pearson() const; // get correlation coefficient.
// Returns the x,y means as an FCOORD.
FCOORD mean_point() const;
// Returns the direction of the fitted line as a unit vector, using the
// least mean squared perpendicular distance. The line runs through the
// mean_point, i.e. a point p on the line is given by:
// p = mean_point() + lambda * vector_fit() for some real number lambda.
// Note that the result (0<=x<=1, -1<=y<=-1) is directionally ambiguous
// and may be negated without changing its meaning.
FCOORD vector_fit() const;
// Returns the covariance.
double covariance() const {
if (total_weight > 0.0)
return (sigxy - sigx * sigy / total_weight) / total_weight;
else
return 0.0;
}
double x_variance() const {
if (total_weight > 0.0)
return (sigxx - sigx * sigx / total_weight) / total_weight;
else
return 0.0;
}
double y_variance() const {
if (total_weight > 0.0)
return (sigyy - sigy * sigy / total_weight) / total_weight;
else
return 0.0;
}
private:
double total_weight; // no of elements or sum of weights.
double sigx; // sum of x
double sigy; // sum of y
double sigxx; // sum x squared
double sigxy; // sum of xy
double sigyy; // sum y squared
};
#endif // TESSERACT_CCSTRUCT_LINLSQ_H_
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