82 lines
2.6 KiB
C++
82 lines
2.6 KiB
C++
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/*
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**************************************************************
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* C++ Mathematical Expression Toolkit Library *
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* *
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* Simple Example 8 *
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* Author: Arash Partow (1999-2013) *
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* URL: http://www.partow.net/programming/exprtk/index.html *
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* *
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* Copyright notice: *
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* Free use of the Mathematical Expression Toolkit Library is *
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* permitted under the guidelines and in accordance with the *
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* most current version of the Common Public License. *
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* http://www.opensource.org/licenses/cpl1.0.php *
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* *
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**************************************************************
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*/
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#include <cstdio>
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#include <string>
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#include "exprtk.hpp"
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template <typename T>
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void composite()
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{
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typedef exprtk::symbol_table<T> symbol_table_t;
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typedef exprtk::expression<T> expression_t;
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typedef exprtk::parser<T> parser_t;
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typedef exprtk::parser_error::type error_t;
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typedef exprtk::function_compositor<T> compositor_t;
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compositor_t compositor;
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T x = T(1);
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T y = T(2);
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symbol_table_t& symbol_table = compositor.symbol_table();
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symbol_table.add_constants();
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symbol_table.add_variable("x",x);
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symbol_table.add_variable("y",y);
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compositor.add("f","sin(x/pi)","x"); // f(x) = sin(x/pi)
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compositor.add("g","3*[f(x)+f(y)]","x","y"); // g(x,y) = 3[f(x)+f(y)]
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std::string expression_string = "g(1 + f(x),f(y) / 2)";
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expression_t expression;
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expression.register_symbol_table(symbol_table);
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parser_t parser;
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if (!parser.compile(expression_string,expression))
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{
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printf("Error: %s\tExpression: %s\n",
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parser.error().c_str(),
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expression_string.c_str());
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for (std::size_t i = 0; i < parser.error_count(); ++i)
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{
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error_t error = parser.get_error(i);
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printf("Error: %02d Position: %02d Type: [%14s] Msg: %s\tExpression: %s\n",
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static_cast<unsigned int>(i),
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static_cast<unsigned int>(error.token.position),
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exprtk::parser_error::to_str(error.mode).c_str(),
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error.diagnostic.c_str(),
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expression_string.c_str());
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}
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return;
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}
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T result = expression.value();
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printf("%s = %e\n", expression_string.c_str(), result);
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}
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int main()
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{
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composite<double>();
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return 0;
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}
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