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Thread Subject:
fmin for integer values (discrete optimization)

Subject: fmin for integer values (discrete optimization)

From: Elnaz

Date: 19 Apr, 2012 22:10:33

Message: 1 of 6

Hi all,

I'm trying to implement a fmin... algorithm over integer values which are used to index a matrix. In other words, I am trying to minimize a function by addressing different elements of a matrix. What would you suggest as the best and quick solution for this?

Thanks,
Elnaz

Subject: fmin for integer values (discrete optimization)

From: Matt J

Date: 20 Apr, 2012 00:08:19

Message: 2 of 6

"Elnaz " <ebsadeghian@gmail.com> wrote in message <jmq2gp$7qr$1@newscl01ah.mathworks.com>...
> Hi all,
>
> I'm trying to implement a fmin... algorithm over integer values which are used to index a matrix. In other words, I am trying to minimize a function by addressing different elements of a matrix. What would you suggest as the best and quick solution for this?
==================

The MIN command?

Subject: fmin for integer values (discrete optimization)

From: Elnaz

Date: 20 Apr, 2012 03:45:36

Message: 3 of 6

> The MIN command?

What do you mean? There is a cost function which depends on how and what elements of a huge matrix (image) are being addressed. I've tried GA but takes long and is not optimum in my case.

Subject: fmin for integer values (discrete optimization)

From: Roger Stafford

Date: 20 Apr, 2012 04:02:32

Message: 4 of 6

"Elnaz " <ebsadeghian@gmail.com> wrote in message <jmq2gp$7qr$1@newscl01ah.mathworks.com>...
> I'm trying to implement a fmin... algorithm over integer values which are used to index a matrix. In other words, I am trying to minimize a function by addressing different elements of a matrix. What would you suggest as the best and quick solution for this?
- - - - - - - - - -
  You've omitted some rather crucial information in your problem description. What is the nature of these indices that determine the value of the function you are trying to minimize and in particular how many of them are needed and what is their range of possible values for each such determination? You need to give a lot more information about your problem to get effective help.

Roger Stafford

Subject: fmin for integer values (discrete optimization)

From: Elnaz

Date: 20 Apr, 2012 04:39:07

Message: 5 of 6

"Roger Stafford" wrote in message <jmqn4o$r24$1@newscl01ah.mathworks.com>...
> You've omitted some rather crucial information in your problem description. What is the nature of these indices that determine the value of the function you are trying to minimize and in particular how many of them are needed and what is their range of possible values for each such determination? You need to give a lot more information about your problem to get effective help.
>
> Roger Stafford

Right; this is a synchronization and detection problem. I have a huge image matrix which I am trying to locate the position of the recorded information in it. The matrix is originally produced by putting bits of information in exact positions but then they have interfered with each other and have noise added. Then, I am supposed to use an optimization algo to tell me where to read those information to minimize the detecting error. Therefor, the optimization algo should pass two elements (row and column) of the matrix in order to minimmize my cost function which is the detection error. The range of the two integer params is small say between 0:10.

Elnaz

Subject: fmin for integer values (discrete optimization)

From: Matt J

Date: 20 Apr, 2012 08:41:12

Message: 6 of 6

"Elnaz " <ebsadeghian@gmail.com> wrote in message <jmqp9b$5qa$1@newscl01ah.mathworks.com>...
>
>
> Right; this is a synchronization and detection problem. I have a huge image matrix which I am trying to locate the position of the recorded information in it. The matrix is originally produced by putting bits of information in exact positions but then they have interfered with each other and have noise added. Then, I am supposed to use an optimization algo to tell me where to read those information to minimize the detecting error. Therefor, the optimization algo should pass two elements (row and column) of the matrix in order to minimmize my cost function which is the detection error. The range of the two integer params is small say between 0:10.
=============================

So that we can best understand what's going on, you should write show us, in equation form, the dependence of your cost function on this huge matrix.

If you're trying to solve for only 2 parameters each ranging between 0:10, you have only 121 different parameter combinations to choose from. It begs the question why you don't just evaluate the function at all 121 possibilities and minimize by exhaustive search (using the MIN command).

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