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/*
**************************************************************
* C++ Mathematical Expression Toolkit Library *
* *
* Simple Example 09 *
* 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 primes()
{
typedef exprtk::symbol_table<T> symbol_table_t;
typedef exprtk::expression<T> expression_t;
typedef exprtk::parser<T> parser_t;
typedef exprtk::function_compositor<T> compositor_t;
typedef typename compositor_t::function function_t;
T x = T(0);
symbol_table_t symbol_table;
symbol_table.add_constants();
symbol_table.add_variable("x",x);
compositor_t compositor(symbol_table);
//Mode 1 - if statement based
compositor.add(
function_t("is_prime_impl1")
.vars("x", "y")
.expression
(
" if (y == 1,true, "
" if (0 == (x % y),false, "
" is_prime_impl1(x,y - 1))) "
));
compositor.add(
function_t("is_prime1")
.var("x")
.expression
(
" if (frac(x) != 0) "
" return [false]; "
" else if (x <= 0) "
" return [false]; "
" else "
" is_prime_impl1(x,min(x - 1,trunc(sqrt(x)) + 1)); "
));
//Mode 2 - switch statement based
compositor.add(
function_t("is_prime_impl2")
.vars("x", "y")
.expression
(
" switch "
" { "
" case y == 1 : true; "
" case (x % y) == 0 : false; "
" default : is_prime_impl2(x,y - 1); "
" } "
));
compositor.add(
function_t("is_prime2")
.var("x")
.expression
(
" switch "
" { "
" case x <= 0 : false; "
" case frac(x) != 0 : false; "
" default : is_prime_impl2(x,min(x - 1,trunc(sqrt(x)) + 1)); "
" } "
));
//Mode 3 - switch statement and for-loop based
compositor.add(
function_t("is_prime3")
.var("x")
.expression
(
" switch "
" { "
" case x <= 1 : return [false]; "
" case frac(x) != 0 : return [false]; "
" case x == 2 : return [true ]; "
" }; "
" "
" var prime_lut[27] := "
" { "
" 2, 3, 5, 7, 11, 13, 17, 19, 23, "
" 29, 31, 37, 41, 43, 47, 53, 59, 61, "
" 67, 71, 73, 79, 83, 89, 97, 101, 103 "
" }; "
" "
" var upper_bound := min(x - 1, trunc(sqrt(x)) + 1); "
" "
" for (var i := 0; i < prime_lut[]; i += 1) "
" { "
" if (prime_lut[i] >= upper_bound) "
" return [true]; "
" else if ((x % prime_lut[i]) == 0) "
" return [false]; "
" }; "
" "
" var lower_bound := prime_lut[prime_lut[] - 1] + 2; "
" "
" for (var i := lower_bound; i < upper_bound; i += 2) "
" { "
" if ((x % i) == 0) "
" { "
" return [false]; "
" } "
" }; "
" "
" return [true]; "
));
std::string expression_str1 = "is_prime1(x)";
std::string expression_str2 = "is_prime2(x)";
std::string expression_str3 = "is_prime3(x)";
expression_t expression1;
expression_t expression2;
expression_t expression3;
expression1.register_symbol_table(symbol_table);
expression2.register_symbol_table(symbol_table);
expression3.register_symbol_table(symbol_table);
parser_t parser;
parser.compile(expression_str1, expression1);
parser.compile(expression_str2, expression2);
parser.compile(expression_str3, expression3);
for (std::size_t i = 0; i < 15000; ++i)
{
x = static_cast<T>(i);
const T result1 = expression1.value();
const T result2 = expression2.value();
const T result3 = expression3.value();
const bool results_concur = (result1 == result2) &&
(result1 == result3) ;
printf("%03d Result1: %c Result2: %c Result3: %c "
"Results Concur: %c\n",
static_cast<unsigned int>(i),
(result1 == T(1)) ? 'T' : 'F',
(result2 == T(1)) ? 'T' : 'F',
(result3 == T(1)) ? 'T' : 'F',
(results_concur) ? 'T' : 'F');
}
}
int main()
{
primes<double>();
return 0;
}
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