/**********************************************************************
 * File:        quadlsq.h  (Formerly qlsq.h)
 * Description: Code for least squares approximation of quadratics.
 * Author:      Ray Smith
 *
 * (C) Copyright 1993, 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 QUADLSQ_H
#define QUADLSQ_H

#include "points.h"

namespace tesseract {

class QLSQ {
public:
  QLSQ() {   // constructor
    clear(); // set to zeros
  }
  void clear(); // initialize

  void add(     // add element
      double x, // coords to add
      double y);
  void remove(  // delete element
      double x, // coords to delete
      double y);
  int32_t count() { // no of elements
    return n;
  }

  void fit(        // fit the given
      int degree); // return actual
  double get_a() const { // get x squard
    return a;
  }
  double get_b() const { // get x squard
    return b;
  }
  double get_c() const { // get x squard
    return c;
  }

private:
  int32_t n;           // no of elements
  double a, b, c;      // result
  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
  long double sigxxx;  // sum x cubed
  long double sigxxy;  // sum xsquared y
  long double sigxxxx; // sum x fourth
};

} // namespace tesseract

#endif