/**********************************************************************

 * 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