C++ Code:    
   
#include <windows.h>    
#include <stdlib.h>    
#include <math.h>    
   
const double SPLIT = 0.01;    
const int COUNT = 200;    
const double PI = 3.14159265;    
const int INTERVAL = 300;    
   
int main()    
{    
    DWORD busySpan[COUNT];    
    DWORD idleSpan[COUNT];    
    int half = INTERVAL / 2;    
    double radian = 0.0;    
    for (int i = 0; i < COUNT; i++)    
     {    
	 busySpan[i] = (DWORD)(half + (sin(PI * radian) * half));    
	 idleSpan[i] = INTERVAL - busySpan[i];    
	 radian += SPLIT;    
     }    
	
    DWORD starttime = 0;    
    int j = 0;    
    while (true)    
     {    
	 j = j % COUNT;    
	 starttime = GetTickCount();    
	 while (GetTickCount() - starttime <= busySpan[j]);    
	 Sleep(idleSpan[j]);    
	 j++;    
     }    
    return 0;    
}    
   

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Visual Basic Code:    
   
Option Explicit    
   
Private Declare Function GetTickCount Lib "kernel32" () As Long    
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)  
  
   
Private Const SPLIT As Double = 0.01    
Private Const COUNT As Long = 200    
Private Const PI   As Double = 3.14159265    
Private Const INTERVAL   As Long = 300    
   
Sub Main()    
Dim busySpan(COUNT) As Long    
Dim idleSpan(COUNT) As Long    
Dim half As Long    
half = INTERVAL / 2    
Dim radian As Double    
Dim i As Long    
   
For i = 0 To COUNT - 1    
     busySpan(i) = half + (Sin(PI * radian) * half)    
     idleSpan(i) = INTERVAL - busySpan(i)    
     radian = radian + SPLIT    
Next i    
Dim starttime As Long    
Dim j As Long    
While (True)    
     j = j Mod COUNT    
     starttime = GetTickCount()    
     While (GetTickCount() - starttime <= busySpan(j))    
     Wend    
     Sleep (idleSpan(j))    
     j = j + 1    
Wend    
End Sub