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exprtk_simple_example_01.cpp
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1 /*
2  **************************************************************
3  * C++ Mathematical Expression Toolkit Library *
4  * *
5  * Simple Example 1 *
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 <string>
21 
22 #include "exprtk.hpp"
23 
24 
25 template <typename T>
26 void trig_function()
27 {
28  typedef exprtk::symbol_table<T> symbol_table_t;
29  typedef exprtk::expression<T> expression_t;
30  typedef exprtk::parser<T> parser_t;
31 
32  std::string expression_string = "clamp(-1.0,sin(2 * pi * x) + cos(x / 2 * pi),+1.0)";
33 
34  T x;
35 
36  symbol_table_t symbol_table;
37  symbol_table.add_variable("x",x);
38  symbol_table.add_constants();
39 
40  expression_t expression;
41  expression.register_symbol_table(symbol_table);
42 
43  parser_t parser;
44  parser.compile(expression_string,expression);
45 
46  for (x = T(-5); x <= T(+5); x += T(0.001))
47  {
48  T y = expression.value();
49  printf("%19.15f\t%19.15f\n",x,y);
50  }
51 }
52 
53 int main()
54 {
55  trig_function<double>();
56  return 0;
57 }