matlab 2nd min question

I have a matrix of 7000 * 7000 in which it contains 0 value and other random ones.(only positive integers). what i want is to identify the minimum value excluding zero and subtract it from all other values, and then compute using my formulas. What i want is that the operation should not touch zero at all. It should leave it as it is....

The output i should get such that nothing happens to zeros but for remaining the min value is identified and subtracted from all.. zero should be left as it is. Dont consider it

Answer 1

[Azzi Abdelmalek]

A=[1 0 2;3 4 5;0 0 4]
b=A(:);
b=b(b~=0)
val=min(b)

%or

B=A  
B(B==0)=inf;
[min_val,idx]=min(B(:))

[rohit venkat gandhi]

can you elaborate and explain me this please? iam a beginner in matlab

[Azzi Abdelmalek]

B=A  
B(B==0)=inf;  % replace all zero values by inf
[min_val,idx]=min(B(:))  %  min_value is the smallest value in B and idx is its corresponding index

Answer 2

[Iain]

 A(A~=0) = A(A~=0) - min(A(A~=0));

This sets each element of A's elements NOT equal to zero equal to A's elements NOT equal to zero, minus the minimum of A's elements NOT equal to 0.