Using the parse-evaluate pattern for high-performance calculations in a loop with a changing variable w/ stopwatch.

ID: 1460

See: DefineVariable, Evaluate, Optimizing Performance in Loops, Parse, Value(double) 
				
					using uCalcSoftware;

var uc = new uCalc();
var variableX = uc.DefineVariable("x");
var userExpression = "x * 2 + 5";
var Total = 0.0;
var UpperBound = 1000000; // One million

// Parse the expression just once before the loop begins.
var parsedExpr = uc.Parse(userExpression);

var stopwatch = System.Diagnostics.Stopwatch.StartNew();
for (double x = 1; x <= UpperBound; x++) {
   variableX.Value(x);
   Total = Total + parsedExpr.Evaluate();
}
stopwatch.Stop();
//Uncomment the following line to reveal the actual speed:
//Console.WriteLine($"Elapsed Milliseconds: {stopwatch.ElapsedMilliseconds} ms");

Console.Write("Sum(1, "); Console.Write(UpperBound); Console.Write(", "); Console.Write(userExpression); Console.Write(") = "); Console.Write(Total);
				
			
Sum(1, 1000000, x * 2 + 5) = 1000006000000
Explore 600+ other examples
				
					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   auto variableX = uc.DefineVariable("x");
   auto userExpression = "x * 2 + 5";
   auto Total = 0.0;
   auto UpperBound = 1000000; // One million

   // Parse the expression just once before the loop begins.
   auto parsedExpr = uc.Parse(userExpression);


   for (double x = 1; x <= UpperBound; x++) {
      variableX.Value(x);
      Total = Total + parsedExpr.Evaluate();
   }

   cout << "Sum(1, " << UpperBound << ", " << userExpression << ") = " << (long long)Total;
}
				
			
Sum(1, 1000000, x * 2 + 5) = 1000006000000
Explore 600+ other examples
				
					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      Dim variableX = uc.DefineVariable("x")
      Dim userExpression = "x * 2 + 5"
      Dim Total = 0.0
      Dim UpperBound = 1000000 '// One million
      
      '// Parse the expression just once before the loop begins.
      Dim parsedExpr = uc.Parse(userExpression)
      
      Dim stopwatch = System.Diagnostics.Stopwatch.StartNew()
      For x  As Double = 1 To UpperBound
         variableX.Value(x)
         Total = Total + parsedExpr.Evaluate()
      Next
      stopwatch.Stop()
      '//Uncomment the following line to reveal the actual speed:
      '//Console.WriteLine($"Elapsed Milliseconds: {stopwatch.ElapsedMilliseconds} ms");
      
      Console.Write("Sum(1, ")
      Console.Write(UpperBound)
      Console.Write(", ")
      Console.Write(userExpression)
      Console.Write(") = ")
      Console.Write(Total)
   End Sub
End Module
				
			
Sum(1, 1000000, x * 2 + 5) = 1000006000000
Explore 600+ other examples