exprtk/exprtk_simple_example_02.cpp at master · ArashPartow/exprtk · GitHub

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**************************************************************

* C++ Mathematical Expression Toolkit Library *

* *

* Simple Example 02 *

* Author: Arash Partow (1999-2025) *

* 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;

}

exprtk/exprtk_simple_example_02.cpp at master · ArashPartow/exprtk · GitHub

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