// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2017 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,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
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//   used to endorse or promote products derived from this software without
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_FUNCTION_SAMPLE_H_
#define CERES_INTERNAL_FUNCTION_SAMPLE_H_

#include <string>

namespace ceres {
namespace internal {

// Clients can use this struct to communicate the value of the
// function and or its gradient at a given point x.
struct FunctionSample {
  FunctionSample()
      : x(0.0),
        value(0.0),
        value_is_valid(false),
        gradient(0.0),
        gradient_is_valid(false) {
  }
  std::string ToDebugString() const;

  double x;
  double value;      // value = f(x)
  bool value_is_valid;
  double gradient;   // gradient = f'(x)
  bool gradient_is_valid;
};

}  // namespace internal
}  // namespace ceres

#endif  // CERES_INTERNAL_FUNCTION_SAMPLE_H_