how to find minimum value in a large matrix

Question

I have a matrix Z eg

Z = randi(6, 20)

I want to find the minimum value from this matrix and display it using x,y coordinates. I got it working once trying to work out the max value, but then replaced max with min in order to work out minimum value. The max works sometimes but the min has never worked, so I'm guessing something is incorrect. I need the min to work!

[x,y]=find(Z==max(max(Z)))
Z_max=Z(x,y))

[x,y]=find(Z==min(min(Z)))
Z_min=Z(x,y))

But I always get an error saying Index exceeds matrix dimensions. When it worked, it gave me answer like this (which is exactly what i want):

x =

     5


y =

     3


Z_max =

    6

Any suggestions will be very helpful.

Answer 1

You need to use the three-ouput version of find . Besides, that also returns the minimum (not only the indices):

[x y min_Z] = find(Z==min(Z(:)));

This will give several values if the minimum is achieved at several entries. If you only want the first, use:

[x y min_Z] = find(Z==min(Z(:)),1);

A possibly faster alternative, which gives only the first:

[min_Z k] = min(Z(:));
[x y] = ind2sub(size(Z),k);