// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2016 Google Inc. All rights reserved.

// http://ceres-solver.org/

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are met:

//

// * Redistributions of source code must retain the above copyright notice,

//   this list of conditions and the following disclaimer.

// * Redistributions in binary form must reproduce the above copyright notice,

//   this list of conditions and the following disclaimer in the documentation

//   and/or other materials provided with the distribution.

// * Neither the name of Google Inc. nor the names of its contributors may be

//   used to endorse or promote products derived from this software without

//   specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

// POSSIBILITY OF SUCH DAMAGE.

//

// Authors: keir@google.com (Keir Mierle), dgossow@google.com (David Gossow)

#include "ceres/is_close.h"

#include <algorithm>

#include <cmath>

namespace ceres {

namespace internal {

bool IsClose(double x, double y, double relative_precision,

             double *relative_error,

             double *absolute_error) {

  double local_absolute_error;

  double local_relative_error;

  if (!absolute_error) {

    absolute_error = &local_absolute_error;

  }

  if (!relative_error) {

    relative_error = &local_relative_error;

  }

  *absolute_error = std::fabs(x - y);

  *relative_error = *absolute_error / std::max(std::fabs(x), std::fabs(y));

  if (x == 0 || y == 0) {

    // If x or y is exactly zero, then relative difference doesn't have any

    // meaning. Take the absolute difference instead.

    *relative_error = *absolute_error;

  }

  return *relative_error < std::fabs(relative_precision);

}

}  // namespace internal

}  // namespace ceres