1 // Ceres Solver - A fast non-linear least squares minimizer
2 // Copyright 2017 Google Inc. All rights reserved.
3 // http://ceres-solver.org/
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6 // modification, are permitted provided that the following conditions are met:
8 // * Redistributions of source code must retain the above copyright notice,
9 // this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above copyright notice,
11 // this list of conditions and the following disclaimer in the documentation
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15 // specific prior written permission.
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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29 // Author: sameeragarwal@google.com (Sameer Agarwal)
31 #ifndef CERES_INTERNAL_FUNCTION_SAMPLE_H_
32 #define CERES_INTERNAL_FUNCTION_SAMPLE_H_
35 #include "ceres/internal/eigen.h"
40 // FunctionSample is used by the line search routines to store and
41 // communicate the value and (optionally) the gradient of the function
44 // Since line search as the name implies happens along a certain
45 // line/direction. FunctionSample contains the information in two
46 // ways. Information in the ambient space and information along the
47 // direction of search.
48 struct FunctionSample {
50 FunctionSample(double x, double value);
51 FunctionSample(double x, double value, double gradient);
53 std::string ToDebugString() const;
55 // x is the location of the sample along the search direction.
58 // Let p be a point and d be the search direction then
60 // vector_x = p + x * d;
62 // True if vector_x has been assigned a valid value.
63 bool vector_x_is_valid;
65 // value = f(vector_x)
67 // True of the evaluation was successful and value is a finite
71 // vector_gradient = Df(vector_position);
73 // D is the derivative operator.
74 Vector vector_gradient;
75 // True if the vector gradient was evaluated and the evaluation was
76 // successful (the value is a finite number).
77 bool vector_gradient_is_valid;
79 // gradient = d.transpose() * vector_gradient
81 // where d is the search direction.
83 // True if the evaluation of the gradient was sucessful and the
84 // value is a finite number.
85 bool gradient_is_valid;
91 } // namespace internal
94 #endif // CERES_INTERNAL_FUNCTION_SAMPLE_H_