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exprtk_simple_example_19.cpp
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1 /*
2  **************************************************************
3  * C++ Mathematical Expression Toolkit Library *
4  * *
5  * Simple Example 19 *
6  * Author: Arash Partow (1999-2019) *
7  * URL: http://www.partow.net/programming/exprtk/index.html *
8  * *
9  * Copyright notice: *
10  * Free use of the Mathematical Expression Toolkit Library is *
11  * permitted under the guidelines and in accordance with the *
12  * most current version of the MIT License. *
13  * http://www.opensource.org/licenses/MIT *
14  * *
15  **************************************************************
16 */
17 
18 
19 #include <cstdio>
20 #include <cstdlib>
21 #include <ctime>
22 #include <string>
23 
24 #include "exprtk.hpp"
25 
26 
27 template <typename T>
28 class randu : public exprtk::igeneric_function<T>
29 {
30 public:
31 
32  typedef typename exprtk::igeneric_function<T> igfun_t;
33  typedef typename igfun_t::parameter_list_t parameter_list_t;
34  typedef typename igfun_t::generic_type generic_type;
35  typedef typename generic_type::vector_view vector_t;
36 
37  using exprtk::igeneric_function<T>::operator();
38 
39  randu()
40  : exprtk::igeneric_function<T>("V|VTT")
41  /*
42  Overloads:
43  0. V - vector
44  1. VTT - vector, r0, r1
45  */
46  { ::srand(static_cast<unsigned int>(time(NULL))); }
47 
48  inline T operator()(const std::size_t& ps_index, parameter_list_t parameters)
49  {
50  vector_t v(parameters[0]);
51 
52  std::size_t r0 = 0;
53  std::size_t r1 = v.size() - 1;
54 
55  if (
56  (1 == ps_index) &&
57  !exprtk::rtl::vecops::helper::
58  load_vector_range<T>::process(parameters,r0,r1,1,2,0)
59  )
60  return T(0);
61 
62  for (std::size_t i = r0; i <= r1; ++i)
63  {
64  v[i] = rnd();
65  }
66 
67  return T(1);
68  }
69 
70 private:
71 
72  inline T rnd()
73  {
74  // Note: Do not use this in production
75  // Result is in the interval [0,1)
76  return T(::rand() / T(RAND_MAX + 1.0));
77  }
78 };
79 
80 template <typename T>
81 void vector_randu()
82 {
83  typedef exprtk::symbol_table<T> symbol_table_t;
84  typedef exprtk::expression<T> expression_t;
85  typedef exprtk::parser<T> parser_t;
86 
87  std::string vecrandu_program =
88  " var noise[6] := [0]; "
89  " "
90  " if (randu(noise,0,5) == false) "
91  " { "
92  " println('Failed to generate noise'); "
93  " return [false]; "
94  " } "
95  " "
96  " var noisy[6] := signal + (noise - 1/2); "
97  " "
98  " for (var i := 0; i < noisy[]; i += 1) "
99  " { "
100  " println('noisy[',i,'] = ', noisy[i]); "
101  " } "
102  " "
103  " println('avg: ', avg(noisy)); "
104  " ";
105 
106  T signal[] = { T(1.1), T(2.2), T(3.3), T(4.4), T(5.5), T(6.6), T(7.7) };
107 
108  exprtk::rtl::io::println<T> println;
109  randu<T> randu;
110 
111  symbol_table_t symbol_table;
112  symbol_table.add_vector ("signal" , signal);
113  symbol_table.add_function("println",println);
114  symbol_table.add_function("randu" , randu);
115 
116  expression_t expression;
117  expression.register_symbol_table(symbol_table);
118 
119  parser_t parser;
120  parser.compile(vecrandu_program,expression);
121 
122  expression.value();
123 }
124 
125 int main()
126 {
127  vector_randu<double>();
128  return 0;
129 }