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
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
// Boost.Units - A C++ library for zero-overhead dimensional analysis and
// unit/quantity manipulation and conversion
//
// Copyright (C) 2003-2008 Matthias Christian Schabel
// Copyright (C) 2008 Steven Watanabe
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
/**
\file
\brief radar_beam_height.cpp
\details
Demonstrate library usage for user test cases suggested by Michael Fawcett.
Output:
@verbatim
//[radar_beam_height_output
radar range : 300 nmi
earth radius : 6.37101e+06 m
beam height 1 : 18169.7 m
beam height 2 : 9.81085 nmi
beam height 3 : 18169.7 m
beam height 4 : 9.81085 nmi
beam height approx : 59488.4 ft
beam height approx : 18132.1 m
//]
@endverbatim
**/
#include <iostream>
#include <boost/units/conversion.hpp>
#include <boost/units/io.hpp>
#include <boost/units/pow.hpp>
#include <boost/units/systems/si.hpp>
#include <boost/units/systems/si/prefixes.hpp>
using boost::units::length_dimension;
using boost::units::pow;
using boost::units::root;
using boost::units::quantity;
using boost::units::unit;
//[radar_beam_height_class_snippet_1
namespace nautical {
struct length_base_unit :
boost::units::base_unit<length_base_unit, length_dimension, 1>
{
static std::string name() { return "nautical mile"; }
static std::string symbol() { return "nmi"; }
};
typedef boost::units::make_system<length_base_unit>::type system;
/// unit typedefs
typedef unit<length_dimension,system> length;
static const length mile,miles;
} // namespace nautical
// helper for conversions between nautical length and si length
BOOST_UNITS_DEFINE_CONVERSION_FACTOR(nautical::length_base_unit,
boost::units::si::meter_base_unit,
double, 1.852e3);
//]
//[radar_beam_height_class_snippet_2
namespace imperial {
struct length_base_unit :
boost::units::base_unit<length_base_unit, length_dimension, 2>
{
static std::string name() { return "foot"; }
static std::string symbol() { return "ft"; }
};
typedef boost::units::make_system<length_base_unit>::type system;
/// unit typedefs
typedef unit<length_dimension,system> length;
static const length foot,feet;
} // imperial
// helper for conversions between imperial length and si length
BOOST_UNITS_DEFINE_CONVERSION_FACTOR(imperial::length_base_unit,
boost::units::si::meter_base_unit,
double, 1.0/3.28083989501312);
//]
// radar beam height functions
//[radar_beam_height_function_snippet_1
template<class System,typename T>
constexpr
quantity<unit<boost::units::length_dimension,System>,T>
radar_beam_height(const quantity<unit<length_dimension,System>,T>& radar_range,
const quantity<unit<length_dimension,System>,T>& earth_radius,
T k = 4.0/3.0)
{
return quantity<unit<length_dimension,System>,T>
(pow<2>(radar_range)/(2.0*k*earth_radius));
}
//]
//[radar_beam_height_function_snippet_2
template<class return_type,class System1,class System2,typename T>
constexpr
return_type
radar_beam_height(const quantity<unit<length_dimension,System1>,T>& radar_range,
const quantity<unit<length_dimension,System2>,T>& earth_radius,
T k = 4.0/3.0)
{
// need to decide which system to use for calculation
return pow<2>(static_cast<return_type>(radar_range))
/ (2.0*k*static_cast<return_type>(earth_radius));
}
//]
//[radar_beam_height_function_snippet_3
constexpr
quantity<imperial::length>
radar_beam_height(const quantity<nautical::length>& range)
{
return quantity<imperial::length>
(pow<2>(range/(1.23*nautical::miles/root<2>(imperial::feet))));
}
//]
int main(void)
{
using namespace boost::units;
using namespace boost::units::si;
using namespace nautical;
//[radar_beam_height_snippet_1
const quantity<nautical::length> radar_range(300.0*miles);
const quantity<si::length> earth_radius(6371.0087714*kilo*meters);
const quantity<si::length> beam_height_1(radar_beam_height(quantity<si::length>(radar_range),earth_radius));
const quantity<nautical::length> beam_height_2(radar_beam_height(radar_range,quantity<nautical::length>(earth_radius)));
const quantity<si::length> beam_height_3(radar_beam_height< quantity<si::length> >(radar_range,earth_radius));
const quantity<nautical::length> beam_height_4(radar_beam_height< quantity<nautical::length> >(radar_range,earth_radius));
//]
std::cout << "radar range : " << radar_range << std::endl
<< "earth radius : " << earth_radius << std::endl
<< "beam height 1 : " << beam_height_1 << std::endl
<< "beam height 2 : " << beam_height_2 << std::endl
<< "beam height 3 : " << beam_height_3 << std::endl
<< "beam height 4 : " << beam_height_4 << std::endl
<< "beam height approx : " << radar_beam_height(radar_range)
<< std::endl
<< "beam height approx : "
<< quantity<si::length>(radar_beam_height(radar_range))
<< std::endl << std::endl;
return 0;
}
|
