1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_FUNCTIONS_ANALYTICFUNCTIONS_POLYNOMIAL_HH
#define DUNE_FUNCTIONS_ANALYTICFUNCTIONS_POLYNOMIAL_HH
namespace Dune {
namespace Functions {
/**
* \brief A scalar polynomial implementation
*
* \ingroup FunctionImplementations
*
* \tparam K Scalar type. The polynomial will map K to K
*
* This class exists mainly to demonstrate how to implement
* the \ref Concept::DifferentiableFunction<Range(Domain), DerivativeTraits> concept.
*/
template<class K>
class Polynomial
{
public:
//! Default constructor
Polynomial() = default;
//! Copy constructor
Polynomial(const Polynomial& other) = default;
//! Move constructor
Polynomial(Polynomial&& other) = default;
/**
* \brief Create from list of coefficients
*
* Coefficients are ordered in accordance with
* the corresponding monomial order
*/
Polynomial(std::initializer_list<double> coefficients) :
coefficients_(coefficients)
{}
/**
* \brief Create from list of coefficients
*
* Coefficients are ordered in accordance with
* the corresponding monomial order. This will
* move the coefficients from givven vector.
*/
Polynomial(std::vector<K>&& coefficients) :
coefficients_(std::move(coefficients))
{}
/**
* \brief Create from list of coefficients
*
* Coefficients are ordered in accordance with
* the corresponding monomial order. This will
* copy coefficients from given vector.
*/
Polynomial(const std::vector<K>& coefficients) :
coefficients_(coefficients)
{}
//! Evaluate polynomial
K operator() (const K& x) const
{
auto y = K(0);
for (size_t i=0; i<coefficients_.size(); ++i)
y += coefficients_[i] * std::pow(x, i);
return y;
}
/**
* \brief Obtain derivative of Polynomial function
*
* \ingroup FunctionImplementations
*
* The derivative contains its own coefficient
* list and is not updated if the original function
* is changed.
*/
friend Polynomial derivative(const Polynomial& p)
{
std::vector<K> dpCoefficients(p.coefficients().size()-1);
for (size_t i=1; i<p.coefficients_.size(); ++i)
dpCoefficients[i-1] = p.coefficients()[i]*i;
return Polynomial(std::move(dpCoefficients));
}
//! Obtain reference to coefficient vector
const std::vector<K>& coefficients() const
{
return coefficients_;
}
private:
std::vector<K> coefficients_;
};
}} // namespace Dune::Functions
#endif // DUNE_FUNCTIONS_ANALYTICFUNCTIONS_POLYNOMIAL_HH
|
