Finding corners of a matrix inside a matrix.

I have a matrix of size 50*80 which contains non-zero values in the center of matrix. for example-- I would like to extract the position of the corner elements in that matrix i.e position of (0,0,5,7) elements. Can anyone help me with the code?

A=[0 0 0 0 0 0 0 0 ;
 0 0 0 2 4 5 0 0;
 0 0 4 0 5 2 1 0;
 0 0 5 8 7 6 7 0;
 0 0 0 0 0 0 0 0;
end

Answer 1

[Birdman]

[r,c]=find(A~=0);
upperLeft=A(min(r),min(c))
lowerLeft=A(max(r),min(c))
upperRight=A(min(r),max(c))
lowerRight=A(max(r),max(c))

[Swapnil Rane]

Thank you for the solution but I want the position of the corners i.e row & column number of the corner elements.

[Stephen23]

@Swapnil Rane: that is what Birdman showed you: min(r),min(c), etc.

[Swapnil Rane]

I don't get it. The output should give me the row & column number i.e upper left=[2,3] lowerleft=[4,3] ...etc.

[KL]

store it in a cell array maybe,

 corners = {[min(r),min(c)],[min(r),max(c)];[max(r),min(c)],[max(r),max(c)]}

[Stephen23]

upperLeft = [min(r),min(c)]
etc.

[Swapnil Rane]

 @KL and @Stephen Cobeldick, both of the code works for me.
Thank you, I really appreciate it.