How can I change Indexing of a Matrix?

I want to change the index values of my matrix .

A = [ 1 3 4 5 7

2 2 1 1 8

3 8 1 2 5

9 7 4 3 3

1 9 3 0 2]

now if i run A(3,3) my answer will be 1,

A(1,1) my answer will be 1 and so on..

but i want to change the indexes of my matrix , such if i type A(0,0) i should get 1 ( A(0,0) should replace A(3,3)

similarly A(-2,-2) = 1 (A(-2,-2) should replace A(1,1).

How to change the indexes of the matrix such that the center is 0,0 . ?

Answer 1

[Bjorn Gustavsson]

This seems like a "very ambitious idea, with dubious benefits". But I'm not the one to judge, so I'll guess you have some good reasone for doing this, it might help you to get good advice if you clarified those reasons.

Meanwhile you might get something out of this file exchange submission (that offers zero-based indexing, so you will have to do some modification of the code to give it "centre-based indexing"): zero-based-indexable-arrays-oop.

HTH

[Praseetha Puducode Narayanan]

This what I want to do :

1) create a matrix, (-4,-4) to (4,4) which is actually a (9 X 9) matrix. Thus making the center as (0,0)

2) Draw a circle of radius 2 from the center of the matrix .

3) Draw a line from (-4,-4) to (4,4)( approx45/135 degrees)

4)Determine how many points on this line passes through the circle.

(I want to this for multiple lines and multiple angels) It is simple for a line at 90 degrees because the line falls on the matrix values, but when we change the line angel then it covers only few matrix values)

If my issue is understood and if I could get a matrix with required indexes it woule be really helpfull.

[Praseetha Puducode Narayanan]

Also without using the in built functions like meshgrid if that is possible.

[Stephen23]

"... if I could get a matrix with required indexes it woule be really helpfull."

I doubt that. It would be an obfuscated misdirection that will lead you further away from solving your task.

https://xyproblem.info

https://en.wikipedia.org/wiki/XY_problem

[Praseetha Puducode Narayanan]

Okay, Thank You.

[Bjorn Gustavsson]

If I've understood the fundamental mathematics to any degree there will be an infinite number of points along any line-segment through a circle.

That's not the answer to your question, but you have to think about what the question requires. One first step is to do each part you can easily figure out how to do separately, do them separately, then have a think about how to combine these steps and what modifications you need to do to get that done.

Also: there's nothing wrong with using meshgrid.

Finally: Creating a "centred-based" matrix is not at all relevant to this question.