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Function1d.h
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1// -*- LSST-C++ -*-
2/*
3 * Developed for the LSST Data Management System.
4 * This product includes software developed by the LSST Project
5 * (https://www.lsst.org).
6 * See the COPYRIGHT file at the top-level directory of this distribution
7 * for details of code ownership.
8 *
9 * This program is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation, either version 3 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program. If not, see <https://www.gnu.org/licenses/>.
21 */
22#ifndef LSST_AFW_MATH_POLYNOMIALS_Function1d_h_INCLUDED
23#define LSST_AFW_MATH_POLYNOMIALS_Function1d_h_INCLUDED
24
25#include "Eigen/Core"
28
29namespace lsst { namespace geom { namespace polynomials {
30
41template <typename Basis_>
43public:
44
45 using iterator = double *;
46 using const_iterator = double const *;
47
49 using Basis = Basis_;
50
52 explicit Function1d(Basis const & basis) :
53 _basis(basis),
54 _coefficients(Eigen::VectorXd::Zero(basis.size()))
55 {}
56
58 Function1d(Basis const & basis, Eigen::VectorXd const & coefficients) :
59 _basis(basis),
60 _coefficients(coefficients)
61 {
62 assert(basis.size() == static_cast<std::size_t>(_coefficients.size()));
63 }
64
66 template <typename Iterator>
67 Function1d(Basis const & basis, Iterator first, Iterator last) :
68 _basis(basis),
69 _coefficients(basis.size())
70 {
71 assert(std::distance(first, last) == static_cast<std::ptrdiff_t>(basis.size()));
72 std::copy(first, last, &_coefficients[0]);
73 }
74
76 Function1d(Function1d const &) = default;
77
79 Function1d(Function1d &&) = default;
80
82 Function1d & operator=(Function1d const &) = default;
83
86
88
89 iterator begin() { return _coefficients.data(); }
90 iterator end() { return begin() + size(); }
91 const_iterator cbegin() const { return _coefficients.data(); }
92 const_iterator cend() const { return begin() + size(); }
93 const_iterator begin() const { return _coefficients.data(); }
94 const_iterator end() const { return begin() + size(); }
96
98 Basis const & getBasis() const { return _basis; }
99
101 std::size_t size() const { return _basis.size(); }
102
104 double operator()(double x, SumMode mode=SumMode::FAST) const {
105 return _basis.sumWith(x, _coefficients, mode);
106 }
107
109
114 double & operator[](std::size_t n) { return begin()[n]; }
115 double const & operator[](std::size_t n) const { return begin()[n]; }
117
119
126 // Return a block view to ensure the caller only modify the values, not the size.
127 return _coefficients.head(size());
128 }
129 auto getCoefficients() const { return _coefficients.head(size()); }
131
134 return Function1d<typename Basis::Scaled>(getBasis().scaled(scaling), _coefficients);
135 }
136
137private:
138 Basis _basis;
139 Eigen::VectorXd _coefficients;
140};
141
143template <typename Basis>
144Function1d<Basis> makeFunction1d(Basis const & basis, Eigen::VectorXd const & coefficients) {
145 return Function1d<Basis>(basis, coefficients);
146}
147
149template <typename Basis, typename Iterator>
150Function1d<Basis> makeFunction1d(Basis const & basis, Iterator first, Iterator last) {
151 return Function1d<Basis>(basis, first, last);
152}
153
154
155}}} // namespace lsst::geom::polynomials
156
157#endif // !LSST_AFW_MATH_POLYNOMIALS_Function1d_h_INCLUDED
A 1-d function defined by a series expansion and its coefficients.
Definition Function1d.h:42
double & operator[](std::size_t n)
Return the coefficient associated with the nth basis function.
Definition Function1d.h:114
Function1d(Basis const &basis, Eigen::VectorXd const &coefficients)
Construct with coefficients from an Eigen object.
Definition Function1d.h:58
double operator()(double x, SumMode mode=SumMode::FAST) const
Evaluate the function at the given point.
Definition Function1d.h:104
Function1d(Basis const &basis)
Construct with zero-valued coefficients.
Definition Function1d.h:52
const_iterator begin() const
Definition Function1d.h:93
Basis const & getBasis() const
Return the associated Basis1d object.
Definition Function1d.h:98
Function1d(Basis const &basis, Iterator first, Iterator last)
Construct by copying coefficients from an STL iterator range.
Definition Function1d.h:67
Function1d(Function1d &&)=default
Default move constructor.
iterator begin()
Iterators over coefficients.
Definition Function1d.h:89
Function1d(Function1d const &)=default
Default copy constructor.
const_iterator cbegin() const
Definition Function1d.h:91
Function1d & operator=(Function1d const &)=default
Default copy assignment.
Function1d< typename Basis::Scaled > scaled(Scaling1d const &scaling) const
Return a new function that applies the given scaling to all points before evaluation.
Definition Function1d.h:133
const_iterator cend() const
Definition Function1d.h:92
double const & operator[](std::size_t n) const
Definition Function1d.h:115
const_iterator end() const
Definition Function1d.h:94
auto getCoefficients()
Return the coefficient vector as an Eigen matrix-like object.
Definition Function1d.h:125
Function1d & operator=(Function1d &&)=default
Default move assignment.
std::size_t size() const noexcept
Return the number of elements in the basis.
A 1-d affine transform that can be used to map one interval to another.
Definition Scaling1d.h:46
T copy(T... args)
T distance(T... args)
Low-level polynomials (including special polynomials) in C++.
Function1d< Basis > makeFunction1d(Basis const &basis, Eigen::VectorXd const &coefficients)
Create a Function1d of the appropriate type from a Basis1d and an Eigen object containing coefficient...
Definition Function1d.h:144
SumMode
Enum used to control how to sum polynomial terms.
Definition SafeSum.h:32
@ FAST
Summation using regular floating-point addition.
Definition SafeSum.h:34