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C++ Mathematical Expression Library (ExprTk) https://www.partow.net/programming/exprtk/index.html

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ArashPartow
2024-01-01 00:00:00 +00:00
committed by Arash Partow
parent f46bffcd69
commit cc1b800c2b
33 changed files with 67415 additions and 54230 deletions
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64
exprtk_simple_example_10.cpp
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@ -3,7 +3,7 @@
* C++ Mathematical Expression Toolkit Library *
* *
* Simple Example 10 *
* Author: Arash Partow (1999-2023) *
* Author: Arash Partow (1999-2024) *
* URL: https://www.partow.net/programming/exprtk/index.html *
* *
* Copyright notice: *
@ -11,6 +11,7 @@
* 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 *
* *
**************************************************************
*/
@ -41,28 +42,29 @@ void newton_sqrt()
compositor_t compositor(symbol_table);
compositor
.add(
function_t( // define function: newton_sqrt(x)
"newton_sqrt",
" switch "
" { "
" case x < 0 : null; "
" case x == 0 : 0; "
" case x == 1 : 1; "
" default: "
" ~{ "
" var z := 100; "
" var sqrt_x := x / 2; "
" repeat "
" if (equal(sqrt_x^2, x)) "
" break[sqrt_x]; "
" else "
" sqrt_x := (1 / 2) * (sqrt_x + (x / sqrt_x)); "
" until ((z -= 1) <= 0); "
" }; "
" } ",
"x"));
compositor.add(
function_t("newton_sqrt")
.var("x")
.expression
(
" switch "
" { "
" case x < 0 : null; "
" case x == 0 : 0; "
" case x == 1 : 1; "
" default: "
" { "
" var remaining_itrs := 100; "
" var sqrt_x := x / 2; "
" repeat "
" if (equal(sqrt_x * sqrt_x, x)) "
" break[sqrt_x]; "
" else "
" sqrt_x := (1 / 2) * (sqrt_x + (x / sqrt_x)); "
" until ((remaining_itrs -= 1) <= 0); "
" }; "
" } "
));
const std::string expression_str = "newton_sqrt(x)";
@ -72,16 +74,20 @@ void newton_sqrt()
parser_t parser;
parser.compile(expression_str,expression);
for (std::size_t i = 0; i < 100; ++i)
for (x = T(0); x < T(500); x += T(0.5))
{
x = static_cast<T>(i);
const T result = expression.value();
const T real = std::sqrt(x);
const T error = std::abs(result - real);
printf("sqrt(%03d) - Result: %15.13f\tReal: %15.13f\n",
static_cast<unsigned int>(i),
const bool err_in_bound = error <= exprtk::details::numeric::constant::pi;
printf("sqrt(%6.2f) - Result: %15.13f\tReal: %15.13f\tError: %18.16f EIB: %c\n",
x,
result,
std::sqrt(x));
real,
error,
err_in_bound ? 'T' : 'F');
}
}