Add ExprTk_BUILD_EXAMPLES to build examples

Also move examples into an examples folder
2025-06-22 16:28:57 +00:00 · 2023-02-25 15:01:05 -05:00
parent 2c35cb4e74
commit 1491ae63ca
21 changed files with 78 additions and 19 deletions
--- a/examples/exprtk_simple_example_10.cpp
+++ b/examples/exprtk_simple_example_10.cpp
@ -0,0 +1,91 @@
+/*
+ **************************************************************
+ *         C++ Mathematical Expression Toolkit Library        *
+ *                                                            *
+ * Simple Example 10                                          *
+ * Author: Arash Partow (1999-2023)                           *
+ * 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                    *
+ *                                                            *
+ **************************************************************
+*/
+
+
+#include <cmath>
+#include <cstdio>
+#include <string>
+
+#include "exprtk.hpp"
+
+template <typename T>
+void newton_sqrt()
+{
+   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);
+
+   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"));
+
+   const std::string expression_str = "newton_sqrt(x)";
+
+   expression_t expression;
+   expression.register_symbol_table(symbol_table);
+
+   parser_t parser;
+   parser.compile(expression_str,expression);
+
+   for (std::size_t i = 0; i < 100; ++i)
+   {
+      x = static_cast<T>(i);
+
+      const T result = expression.value();
+
+      printf("sqrt(%03d) - Result: %15.13f\tReal: %15.13f\n",
+             static_cast<unsigned int>(i),
+             result,
+             std::sqrt(x));
+   }
+}
+
+int main()
+{
+   newton_sqrt<double>();
+   return 0;
+}