text: // 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)
  //
  // Utility routine for comparing two values.
  
  #ifndef CERES_INTERNAL_IS_CLOSE_H_
  #define CERES_INTERNAL_IS_CLOSE_H_
  
  #include "ceres/internal/port.h"
  
  namespace ceres {
  namespace internal {
  // Returns true if x and y have a relative (unsigned) difference less than
  // relative_precision and false otherwise. Stores the relative and absolute
  // difference in relative/absolute_error if non-NULL. If one of the two values
  // is exactly zero, the absolute difference will be compared, and relative_error
  // will be set to the absolute difference.
  CERES_EXPORT_INTERNAL bool IsClose(double x,
                                     double y,
                                     double relative_precision,
                                     double* relative_error,
                                     double* absolute_error);
  }  // namespace internal
  }  // namespace ceres
  
  #endif  // CERES_INTERNAL_IS_CLOSE_H_
  