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/*
**************************************************************
* C++ Mathematical Expression Toolkit Library *
* *
* Simple Example 02 *
* Author: Arash Partow (1999-2024) *
* URL: https://www.partow.net/programming/exprtk/index.html *
* *
* Copyright notice: *
* Free use of the Mathematical Expression Toolkit Library is *
* permitted under the guidelines and in accordance with the *
* most current version of the MIT License. *
* https://www.opensource.org/licenses/MIT *
* SPDX-License-Identifier: MIT *
* *
**************************************************************
*/
#include <cstdio>
#include <string>
#include "exprtk.hpp"
template <typename T>
void square_wave()
{
typedef exprtk::symbol_table<T> symbol_table_t;
typedef exprtk::expression<T> expression_t;
typedef exprtk::parser<T> parser_t;
const std::string expression_string =
"a *(4 / pi) * "
"((1 / 1) * sin( 2 * pi * f * t) + (1 / 3) * sin( 6 * pi * f * t) + "
" (1 / 5) * sin(10 * pi * f * t) + (1 / 7) * sin(14 * pi * f * t) + "
" (1 / 9) * sin(18 * pi * f * t) + (1 / 11) * sin(22 * pi * f * t) + "
" (1 / 13) * sin(26 * pi * f * t) + (1 / 15) * sin(30 * pi * f * t) + "
" (1 / 17) * sin(34 * pi * f * t) + (1 / 19) * sin(38 * pi * f * t) + "
" (1 / 21) * sin(42 * pi * f * t) + (1 / 23) * sin(46 * pi * f * t) + "
" (1 / 25) * sin(50 * pi * f * t) + (1 / 27) * sin(54 * pi * f * t)) ";
static const T pi = T(3.141592653589793238462643383279502);
const T f = pi / T(10);
const T a = T(10);
T t = T(0);
symbol_table_t symbol_table;
symbol_table.add_variable("t",t);
symbol_table.add_constant("f",f);
symbol_table.add_constant("a",a);
symbol_table.add_constants();
expression_t expression;
expression.register_symbol_table(symbol_table);
parser_t parser;
parser.compile(expression_string,expression);
const T delta = (T(4) * pi) / T(1000);
for (t = (T(-2) * pi); t <= (T(+2) * pi); t += delta)
{
const T result = expression.value();
printf("%19.15f\t%19.15f\n", t, result);
}
}
int main()
{
square_wave<double>();
return 0;
}
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