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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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46
exprtk_simple_example_16.cpp
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@ -3,7 +3,7 @@
* C++ Mathematical Expression Toolkit Library *
* *
* Simple Example 16 *
* 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 *
* *
**************************************************************
*/
@ -31,24 +32,27 @@ void linear_least_squares()
typedef exprtk::parser<T> parser_t;
const std::string linear_least_squares_program =
" if (x[] == y[]) "
" { "
" beta := (sum(x * y) - sum(x) * sum(y) / x[]) / "
" (sum(x^2) - sum(x)^2 / x[]); "
" "
" alpha := avg(y) - beta * avg(x); "
" "
" rmse := sqrt(sum((beta * x + alpha - y)^2) / y[]); "
" } "
" else "
" { "
" alpha := null; "
" beta := null; "
" rmse := null; "
" } ";
" if (x[] == y[]) "
" { "
" var mean_x := avg(x); "
" var mean_y := avg(y); "
" "
" beta := sum((x - mean_x) * (y - mean_y)) / "
" sum((x - mean_x)^2); "
" "
" alpha := mean_y - beta * mean_x; "
" "
" rmse := sqrt(sum((beta * x + alpha - y)^2) / y[]); "
" } "
" else "
" { "
" alpha := null; "
" beta := null; "
" rmse := null; "
" } ";
T x[] = {T( 1), T( 2), T(3), T( 4), T( 5), T(6), T( 7), T( 8), T( 9), T(10)};
T y[] = {T(8.7), T(6.8), T(6), T(5.6), T(3.8), T(3), T(2.4), T(1.7), T(0.4), T(-1)};
T x[] = { T(1.0), T(2.0), T(3.0), T(4.0), T(5.0), T(6.0), T(7.0), T(8.0), T(9.0), T(10) };
T y[] = { T(8.7), T(6.8), T(6.0), T(5.6), T(3.8), T(3.0), T(2.4), T(1.7), T(0.4), T(-1) };
T alpha = T(0);
T beta = T(0);
@ -65,7 +69,11 @@ void linear_least_squares()
expression.register_symbol_table(symbol_table);
parser_t parser;
parser.compile(linear_least_squares_program,expression);
if (!parser.compile(linear_least_squares_program,expression))
{
printf("error: %s\n",parser.error().c_str());
return;
}
expression.value();