Getting a random positive/negative value

[anselm Hexicola]

As part of of an (already unwieldy) script I am writing, I want to flip numeric values randomly between + and -.

Now, I came up with some lines that seem to do what I want.

 

integer sign;
float arbitrary_float= 0.5;

determine_boolean()
{
	float rand1=llFrand(arbitrary_float);
	float rand2=llFrand(arbitrary_float);

	if (rand1>rand2)
		sign=TRUE;
		
	else if (rand1<rand2)
		sign=FALSE;
	
	else
		determine_boolean();
}
	
default
{
	touch_start(integer total_number)
	{
		determine_boolean();
		llOwnerSay("sign is "+(string)sign);
	}
}

 

1. As I say, it  seems to work for me.

2. But, is there a problem with the final "Else"? I only added that to cover the eventuality that both rand1 and rand2 outputted identically.

3. How would this be best done? - ie, generate a random TRUE or FALSE.

[Rolig Loon]

integer DetermineBoolean(){    float Seed = 100.0;    integer Random = (integer)llFrand(Seed);    return Random%2;}

 

[anselm Hexicola]

Ah, odd and even no's.

[irihapeti]

---

anselm Hexicola wrote:

 

2. But, is there a problem with the final "Else"? I only added that to cover the eventuality that both rand1 and rand2 outputted identically.

3. How would this be best done? - ie, generate a random TRUE or FALSE.

---

the problem with 2. is that bc llFrand is uniformly distributed then is possible that the function as wrote wont ever return. Is potential that it can always gen the same numbers and the script will go catatonic

from programmer/scripter pov catatonic also incl. cycles of 2 or more to get the result you want when can get result in 1 cycle. Is best to avoid coding this way

for 3. if do just want TRUE | FALSE then

integer sign = (integer)llFrand(2);  // 0 false. 1 true

 eta: cast

 

 

[Madelaine McMasters]

Hi anselm,

I'm going to work only from your statement "I want to flip numeric values randomly between + and -", without referring to your example code, which doesn't actually do that.

;-)

 

float randomPolarity(float input){    return( llRound(llFrand(1.0)) *2 -1)*input;}

 

[anselm Hexicola]

That is tidy and compact indeed.

(And, yes, I did realise that my own lines would need another few to finally get what I wanted.)

[ ..which is why I always am dismayed by the eventual size of my scripts ...]

[anselm Hexicola]

---

irihapeti wrote:

---

---

 

for 3. if do just want TRUE | FALSE then

integer sign = (integer)llFrand(2); 

 

 

---

 

Yes, that is nice,short and elegant. (Thankyou)

With regard to 2., in my heart of hearts I knew it wasn't right...

[anselm Hexicola]

---

Rolig Loon wrote:

integer DetermineBoolean(){    float Seed = 100.0;    integer Random = (integer)llFrand(Seed);    return Random%2;}

 

I think I get the general logic behind this (ie. generating odd and even numbers); but what I

dont

get is why your float Seed is 100.0.

I spent a bit of time playing with your snippet, running counted iterations, and I got just as reliable results with Seed set at 2.0.

---

 

[Rolig Loon]

Purely arbitrary.  I could have picked any seed.  100.0 was handy.  2.0 works.  And if you wanted a value of -1 or +1 instead of 0 and 1, just write

return 1 - (2 * Random%2);

[irihapeti]

you will be ok

just keep on writing your scripts, asking questions, studying up the wiki and stuff like that and you will grow your knowledge and skills as a scripter

[Madelaine McMasters]

---

anselm Hexicola wrote:

[ ..which is why I always am dismayed by the eventual size of my scripts ...]

---

Welcome to my world, Anselm! I wrote a lot of code over my career in engineering. Along the way, I noticed a pattern to the size of my programs during development. They would start out small, simple, and oh so broken. As I fixed 'em they'd balloon. Then I'd discover that my original concepts were, well, for lack of a better term... stupid. By the time I was done, the code was still larger than I expected at the start, but it was smaller than it was when I first got it working.

A secret to success is to be dismayed by your own own work while it amazes others.

You and I are halfway there.

;-).