Assigning the pixel location

I have the following matrix:

    a =

         1     4
         6     4

After that, I created a zero matrix `new` of the same size of `a`:

    new =

         0     0
         0     0

I'm trying to do the following:

- assign the location `(2,1)` in `a` to the variable `p` - for that location in `new`, I want to give it the value `1`

For that, I did the following:

    p=a(2,1);
    new(p)=1;

But, I got the following:

    In an assignment  A(I) = B, a matrix A cannot be resized.

It seems that also `p=a(2,1);` assigns the value at that location and not the location itself.

How can I solve this issue?

Thanks.

Answer 1

[Image Analyst]

You can use a structure:

p.row = 2;
p.Col = 1;

Or you can use a single number if you use sub2ind to get a linear index

p = sub2ind(matrixSize, row, col);

Chances are that you don't really need to or want to do either of those. Chances are you can just make a logical array but I don't really know how to tell you the best way because I don't have the larger picture/context so all I can do it to tell you exactly what you asked, which like I said is probably not the best approach.