PSLQ and LLL?

anonimnystefy · 2013-03-31 12:26:49

Can't you, please, post the code?

bobbym · 2013-03-31 12:29:26

Okay, I am now pretty sure of it's accuracy:

maze[]:=Module[{box, L={0,0,0,0}},

firstmove=RandomInteger[{1,4}];
If[firstmove==1, box=1;L[[4]]=1];
If[firstmove==2, box=2;L[[4]]=2];
If[firstmove>2, box=3;L[[4]]=3];
Do[
move=RandomInteger[{1,2}];
If [box==1 && move==1,L[[1]]=1;Return[L]];
If [box==1 && move==2,box=2];

move=RandomInteger[{1,3}];
If [box==2 && move==1,box=1];
If [box==2 && move==2,L[[2]]=1;Return[L]];
If [box==2&& move==3,box=3];

move=RandomInteger[{1,3}];
If [box==3&& move==1,box=2];
If [box==3 && move>1,L[[3]]=1;Return[L]],
{100}]
]

ans =Table[maze[],{1000000}];

(Select[ans,#[[3]]==1 && Last[#]==1&]//Length)/(Select[ans,#[[3]]==1 &]//Length)

0.07703891543158152

anonimnystefy · 2013-03-31 12:39:01

Shouldn't you be checking if Last[#] is 1. That is where he enters.

And what is the rest of the list L for?

bobbym · 2013-03-31 12:41:19

The list L contains all that information.

anonimnystefy · 2013-03-31 12:45:10

But, shouldn't you be checking if the third element is 1 and the fourth is 1?

bobbym · 2013-03-31 12:46:45

L[[4]] has the room the rat entered in

L[[1...3]] Has either a 1 or a 0. For instance L={0,1,0,3} would mean the rat entered the maze in room 3 and exited from room 2. L={1,0,0,2} would mean the rat entered the maze in room 2 and exited from room 1.

anonimnystefy · 2013-03-31 12:51:40

Then that means you are selecting the cases where the rat has entered in room 3 and left at room 1!

bobbym · 2013-03-31 12:57:00

Yikes, that is correct. I told you not to rush me! I have adjusted the code.

anonimnystefy · 2013-03-31 12:58:19

You need #[[3]]==1 in the second select as well.

bobbym · 2013-03-31 13:01:02

Hi;

No, that is correct. Last[L] == 1 says it entered the maze in room 1.

anonimnystefy · 2013-03-31 13:05:24

Oh, I tought that was for c).

bobbym · 2013-03-31 13:06:25

That is what I did it for:

(c) If the rat leaves the maze from Room 3 find the probability that it entered at Room 1.

anonimnystefy · 2013-03-31 13:20:17

Well, that probability is P(entered at 1 and left at 3)/P(left at 3). That means the second Select selects the cases when the rat left at three, i.e. when #[[3]]==1.

bobbym · 2013-03-31 13:27:53

Hmmm, I think it should be
( the cases it left at 3 and started at 1) / (cases it started at 1 ).
That is what I have calculated.

anonimnystefy · 2013-03-31 13:35:05

That is not correct. That will give you the answer for a).

bobbym · 2013-03-31 13:45:10

Hi;

How about this way of thinking;

Out of 1000000 tries the rat started in room 1, 250077 times. About 1 / 4 which is
just what we expect. The number of times it left room 3 after starting in room 1 is
38522

38522 / 250077 = 0.15404 which is just what I am getting with mine.

anonimnystefy · 2013-03-31 13:48:22

Yes, but that still answers a).

bobbym · 2013-03-31 13:51:39

Maybe the answers are the same? Is there something wrong with what I did in post #416?

anonimnystefy · 2013-03-31 13:54:44

Yes, there is.

Do we agree that the probability we are looking for is P(entered at 1|left at 3)?

bobbym · 2013-03-31 13:56:10

Yes, that looks good.

anonimnystefy · 2013-03-31 13:57:46

And, do you agree that P(A|B)=P(A and B)/P(B)?

Last edited by anonimnystefy (2013-03-31 13:58:24)

bobbym · 2013-03-31 13:59:52

Yes, that is the definition.

anonimnystefy · 2013-03-31 14:01:36

That means that P(entered at 1|left at 3)=P(entered at 1 and left at 3)/P(left at 3).

bobbym · 2013-03-31 14:06:21

Hmmmm, hard to argue with that one. By golly I think you are right. I did not look at it that way.

anonimnystefy · 2013-03-31 14:08:14

Well, there you have it. What is the new result?

Math Is Fun Forum

#401 2013-03-31 12:26:49

Re: PSLQ and LLL?

#402 2013-03-31 12:29:26

Re: PSLQ and LLL?

#403 2013-03-31 12:39:01

Re: PSLQ and LLL?

#404 2013-03-31 12:41:19

Re: PSLQ and LLL?

#405 2013-03-31 12:45:10

Re: PSLQ and LLL?

#406 2013-03-31 12:46:45

Re: PSLQ and LLL?

#407 2013-03-31 12:51:40

Re: PSLQ and LLL?

#408 2013-03-31 12:57:00

Re: PSLQ and LLL?

#409 2013-03-31 12:58:19

Re: PSLQ and LLL?

#410 2013-03-31 13:01:02

Re: PSLQ and LLL?

#411 2013-03-31 13:05:24

Re: PSLQ and LLL?

#412 2013-03-31 13:06:25

Re: PSLQ and LLL?

#413 2013-03-31 13:20:17

Re: PSLQ and LLL?

#414 2013-03-31 13:27:53

Re: PSLQ and LLL?

#415 2013-03-31 13:35:05

Re: PSLQ and LLL?

#416 2013-03-31 13:45:10

Re: PSLQ and LLL?

#417 2013-03-31 13:48:22

Re: PSLQ and LLL?

#418 2013-03-31 13:51:39

Re: PSLQ and LLL?

#419 2013-03-31 13:54:44

Re: PSLQ and LLL?

#420 2013-03-31 13:56:10

Re: PSLQ and LLL?

#421 2013-03-31 13:57:46

Re: PSLQ and LLL?

#422 2013-03-31 13:59:52

Re: PSLQ and LLL?

#423 2013-03-31 14:01:36

Re: PSLQ and LLL?

#424 2013-03-31 14:06:21

Re: PSLQ and LLL?

#425 2013-03-31 14:08:14

Re: PSLQ and LLL?

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