Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2012-01-31 19:47:41

model
Member
Registered: 2011-08-10
Posts: 142

Bayes' Theorem

Hy guys ,

I did not understand the basic meaning and purpose of Bayes' Theorem . Could any one please elaborate a bit .
Thanks


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#2 2012-01-31 21:34:58

Bob
Administrator
Registered: 2010-06-20
Posts: 10,053

Re: Bayes' Theorem

Hi model

I am not able to draw you a diagram at the moment
but you can look up the one I did recently in thread 17078.

Say you take a card from a pack and then another.

The probability of card two being an ace (let's say )
Will depend on whether card one was an ace.

P(second ace given first ace) = 3/51

But

P(second ace given first not) = 4/51

I have always found a diagram like 17078 sorts out
Most two event problems.

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

Offline

#3 2012-02-01 19:39:58

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

Hy ,

17078 is my question thread . and where is diagram as  you  said in your posted reply ?


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#4 2012-02-01 22:56:17

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,711

Re: Bayes' Theorem


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

Offline

#5 2012-02-01 23:00:52

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

thanks for the  link . smile


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#6 2012-02-10 19:36:06

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

Hy I understood Bayes theorem and Bayesian network .

Let say my hand started motion at point A that initial position  what would be the next position of my hand at point B?

like as shown in this image : http://imageshack.us/photo/my-images/213/10901168.png/


My question is how to know the probability of point A ?


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#7 2012-02-10 20:23:04

kanta
Member
Registered: 2012-01-23
Posts: 1

Re: Bayes' Theorem

Sophia sets off on a walk at a speed of 6 km/h.ten minutes later,her brother Danish sets off after her on his bicycle at 15 km/h. How far must Danish go to catch up with sophia?

please solve.

Offline

#8 2012-02-10 22:22:55

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Hi kanta;

Please post a new thread when you post a new problem. Just tacking it on to someone else's hides their post.

So Danish catches Sophia after 1 / 9 hrs. To get how far he travels

So Danish travels 5 / 3 km.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#9 2012-02-10 22:52:14

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

HY  Bobbym ,

What about my question ?

Last edited by model (2012-02-10 22:52:58)


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#10 2012-02-10 22:53:05

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Hi model;

I am looking at it now.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#11 2012-02-10 23:02:57

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Hi model;

I think we need more information to determine the probability of point A. Do you have any more?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#12 2012-02-10 23:15:55

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

bobbym wrote:

Hi model;

I think we need more information to determine the pobability of point A. Do you have any more?

Hy no, I do't have any information.

but yes one thing.  we could  consider that  10 frames passed then object moved .  I  am also thinking what type of information do i need to get probability of point A.


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#13 2012-02-10 23:18:31

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

You would need to know what part of the graph you can place A and the number of horizontal and vertical pixels of that area.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#14 2012-02-10 23:23:36

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

bobbym wrote:

You would need to know what part of the graph you can place A and the number of horizontal and vertical pixels of that area.

Do you mean that  how much point A covered his distance and area ?


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#15 2012-02-10 23:25:42

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Isn't point A the initial point? The first one?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#16 2012-02-10 23:28:33

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

bobbym wrote:

Isn't point A the initial point? The first one?

hmm yes .. right .  ok  point A is initial point. meant current location.
then what do you mean by this

" You would need to know what part of the graph you can place A and the number of horizontal and vertical pixels of that area. "

Do you meant by moving object area ? like my hand area ?

Last edited by model (2012-02-10 23:30:30)


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#17 2012-02-10 23:31:17

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

If you were to draw an imaginary rectangle around the area where Point A could be placed where would it be?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#18 2012-02-10 23:35:45

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

bobbym wrote:

If you were to draw an imaginary rectangle around the area where Point A could be placed where would it be?

hmm hold on. lemme post  here total image size in form of rectangle area . and a point A(i-e hand) with its coordinates x  and y .  ok

Last edited by model (2012-02-10 23:37:21)


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#19 2012-02-10 23:53:09

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

Hy,

my image area is : 76800

and hand area is : 4592

you can see in this image as link :  http://imageshack.us/photo/my-images/823/imgoy.png/

And now tell me what info do we need to get the probability of my hand as a point A ?

Last edited by model (2012-02-10 23:54:39)


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#20 2012-02-10 23:57:28

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Hold on for a second. Let's go back to post #6. We are looking at a graph which might represent your screen. Can point A start anywhere on the screen? We need to know what is the possible spots where A can be placed initially?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#21 2012-02-11 00:19:02

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

well initial location of  my hand is 0 when there is no hand appear  in the video  but when hand appear any where in the video then location will appear .  Hy  please consider #6 for my work as i shown in the image.


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#22 2012-02-11 06:02:44

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Hi model;

Unless we can get the problem down to something like post #6 we will not be able to say anything about the probabilty.

I will draw you a diagram that will hopefully explain what we need.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#23 2012-02-11 21:08:38

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

bobbym wrote:

Hi model;

Unless we can get the problem down to something like post #6 we will not be able to say anything about the probabilty.

I will draw you a diagram that will hopefully explain what we need.

hmm ok i am waiting for your diagram then . 
and yes thanks for helping me. smile


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

#24 2012-02-11 22:15:05

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Bayes' Theorem

Hi model;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#25 2012-02-12 17:47:17

model
Member
Registered: 2011-08-10
Posts: 142

Re: Bayes' Theorem

bobbym wrote:

Hi model;

I think you meant by this is area of point A, right ?


Maths is Doctor that make our life easy .. smile smile

https://www.facebook.com/groups/Maths.GIS/

Offline

Board footer

Powered by FluxBB