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Random Number Generating

 
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Random Number Generating, I need values between 0-1 or 1-2
Pationate
1 Jun, 2008 - 05:57 AM
Post #1

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CODE

void __fastcall TForm1::FormCreate(TObject *Sender)
{
double y,ygen;
const double A=35434563456.0 ,B=52453456353.0;
double r;
ygen=A*ygen;
ygen=fmod(ygen,B);
r=ygen/B;
y=ygen;
Label1->Caption=r;
}


Well this algorithm returns me a value like ... 8,31191833346667E-318 can i add some calculation to the random number so that it returns a value between 0-1 , 1-2 .
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KYA
RE: Random Number Generating
1 Jun, 2008 - 06:03 AM
Post #2

#include <nerd.h>
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Seed the rand to time

and thus:

cpp

srand ( time(NULL) );

//this will always give a 1 or 2
//You can change the numbers around to give between 0-2
yourNumber = ((rand() %2)+1);
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Pationate
RE: Random Number Generating
1 Jun, 2008 - 06:14 AM
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My tutor ordered me not to use the Rand() function at all times . So i'd prolly have to make a random generating algorithm my self. Eventhough your %2+1 idea is correct. I have to use it in my code , without Rand() .

ps. KYA mate , i really like that you try answering my Questions . Thnx
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KYA
RE: Random Number Generating
1 Jun, 2008 - 06:17 AM
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#include <nerd.h>
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Man, I hate assignments that make you reinvent the wheel.

If you can use a class, Here is a snippet from this site that can help you out.

This post has been edited by KYA: 1 Jun, 2008 - 06:18 AM
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Pationate
RE: Random Number Generating
1 Jun, 2008 - 06:20 AM
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QUOTE(KYA @ 1 Jun, 2008 - 07:17 AM) *

Man, I hate assignments that make you reinvent the wheel.

If you can use a class, Here is a snippet from this site that can help you out.


Agree on that ..
Thnx for the link . I think i'll found out what i need from that .
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NickDMax
RE: Random Number Generating
1 Jun, 2008 - 11:55 AM
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There is a nice smile.gif tutorial on random number generators.

Basically you may want to read up on Linear Congruential Generators. Though Voodoo Doll's Mersenne Twister is actually a better algorithm (but harder to understand if you teacher requires you to be able to explain how it works).

LCG's are pretty basic.
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