ceres-solver/internal/ceres/is_close.cc

// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2016 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
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// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// 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