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

2025-06-12 16:27:23 +00:00 · 2014-06-08 19:24:53 +10:00
parent 4aa02953f8
commit 751226b946
6 changed files with 2464 additions and 544 deletions
--- a/exprtk_simple_example_14.cpp
+++ b/exprtk_simple_example_14.cpp
@ -0,0 +1,59 @@
+/*
+ **************************************************************
+ *         C++ Mathematical Expression Toolkit Library        *
+ *                                                            *
+ * Simple Example 14                                          *
+ * Author: Arash Partow (1999-2014)                           *
+ * URL: http://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 Common Public License.         *
+ * http://www.opensource.org/licenses/cpl1.0.php              *
+ *                                                            *
+ **************************************************************
+*/
+
+
+#include <cstdio>
+#include <cstdlib>
+#include <ctime>
+#include <string>
+#include "exprtk.hpp"
+
+
+template<typename T>
+void stddev_example()
+{
+   typedef exprtk::symbol_table<T> symbol_table_t;
+   typedef exprtk::expression<T>     expression_t;
+   typedef exprtk::parser<T>             parser_t;
+
+   std::string stddev_program =
+                  " var x[25] := {                     "
+                  "                 1,  2,  3,  4,  5, "
+                  "                 6,  7,  8,  9, 10, "
+                  "                11, 12, 13, 14, 15, "
+                  "                16, 17, 18, 19, 20, "
+                  "                21, 22, 23, 24, 25  "
+                  "              };                    "
+                  "                                    "
+                  " sqrt(sum([x - avg(x)]^2) / x[])    ";
+
+   expression_t expression;
+
+   parser_t parser;
+
+   parser.compile(stddev_program,expression);
+
+   T stddev = expression.value();
+
+   printf("stddev(1..25) = %10.6f\n",stddev);
+}
+
+int main()
+{
+   stddev_example<double>();
+   return 0;
+}