Need a little help understanding this math

Blitz3D Forums/Blitz3D Beginners Area/Need a little help understanding this math

CodeOrc

(Posted 2011) [#1]

Unless I am crazy or something which could be the case...in the example below it shows the lowest and highest numbers get picked 50% of the time.

why is that? math fluke?

Graphics3D 800,600,0,2
 SeedRnd MilliSecs()

Repeat 
Cls
 vara=Rnd(1,5)

	If vara = 1 Then varb=varb+1 
	If vara = 2 Then varc=varc+1
	If vara = 3 Then vard=vard+1
	If vara = 4 Then vare=vare+1
	If vara = 5 Then varf=varf+1
		Text 1,1, "vara- the number picker: "+vara
		Text 1,12, "varb: "+varb
		Text 1,24, "varc: "+varc
		Text 1,36, "vard: "+vard
		Text 1,48, "vare: "+vare
		Text 1,60, "varf: "+varf

	UpdateWorld			

RenderWorld()
Flip

Until KeyHit (1)

End

EDIT: after looking, I replaced "Rnd" with "Rand" and it cleared up the problem...weird though ay'?

Last edited 2011

Last edited 2011

Midimaster

(Posted 2011) [#2]

I think, it is because Rnd() is floating point:

1.00 - 1.499 -> 1
1.50 - 2.499 -> 2
.....
4.50 - 4.999 -> 5

and this means the range for getting "1" has a size of 0.5. And the range for getting "2" is 1.0. So "2", "3" and "4" are picked twice as often as "1" and "5"

Matty

(Posted 2011) [#3]

It is because rnd returns a floating point value, but you are storing them in integer variables.

CodeOrc

(Posted 2011) [#4]

thx for the replies...makes sense :)

cheers