CRandomNumberGenerator2

$Revision: 6 $

Description

This class implements a better random number generator than the C runtime library. It uses the Mersenne Twister algorithm. Yehuda Hahn (ygh@cfsnet.com) wrote the C version adapted from http://www.math.keio.ac.jp/matumoto/cokus.c All I did was wrap it in a C++ class.

Methods

DWORD GetInteger( void ): Returns a 32-bit random integer.
double GetFloat( void ): Returns a random float between 0 and 1.
void InitializeSeed( void ): Initializes the seed value for the generator. To increase randomness, it uses a combination of the number of milliseconds the NT machine has been on and the number of free clusters on the current drive to seed the generator.
void SetSeed( DWORD new_seed ): Sets the seed to this value. You can use this if you don't like my method of seeding.

Operators

These are what makes this class cool. You can use the class as a base type.

```
char
```
```
unsigned char
```
```
int
```
```
unsigned int
```
```
short
```
```
unsigned short
```
```
long
```
```
unsigned long
```
```
float
```
```
double
```

Example

#include <wfc.h>
#pragma hdrstop

void test_CRandomNumberGenerator( void )
{
   CRandomNumberGenerator2 random_number;

   int index = 0;

   while( index < 20 )
   {
      _tprintf( TEXT( "DWORD  random number is %lu\n" ), (DWORD)  random_number );
      _tprintf( TEXT( "double random number is %lf\n" ), (double) random_number );

      index++;
   }
}

API's Used

CRandomNumberGenerator2 uses the following API's:

GetDiskFreeSpace
GetSystemTime
GetTickCount

Randomness Test

I'm no mathematician. If you are, please have mercy on me when you read the results of my randomness tests on this generator.

I ran this generator through a few tests that I could think of for randomness. Here's the results for generating 100,000,000 32-bit integers (that makes 3,200,000,000 bits).

Number of 1-bits	1,600,024,395
Number of 0-bits	1,599,975,605
Longest series of 1-bits	31
Longest series of 0-bits	37

Here's a breakdown of the bits in each of the 32 slots that make up a 32-bit integer. The count is the number of times the bit at that location had a value of 1.

Bit Number	Number of 1's
0	50,001,806
1	49,996,289
2	49,998,465
3	49,995,963
4	50,008,188
5	49,991,291
6	50,010,640
7	50,004,980
8	50,002,946
9	49,997,908
10	49,993,413
11	50,004,827
12	49,998,652
13	49,993,790
14	50,000,819
15	49,995,340
16	50,000,634
17	50,004,450
18	49,999,081
19	50,003,646
20	50,001,295
21	50,005,936
22	50,001,090
23	50,003,166
24	50,003,137
25	49,999,151
26	49,998,465
27	50,001,554
28	50,005,453
29	50,010,749
30	49,995,459
31	49,995,812

Copyright, 2000, Samuel R. Blackburn
$Workfile: CRandomNumberGenerator2.cpp $
$Modtime: 2/05/00 8:27a $