if all elemets of a array equal, which array will be choose by MAX function?

Hi

I have an a = [0, 0 , 0 , 0 , 0 ] matrix and when try to use max(a) it always choose the first element as a max value. I need a function like MAX(x) but when all the elements are equal to each other is should choose the one of them randomly. is there any function like that ?

Answer 1

[Stephen23]

There is no inbuilt function, but you can do it yourself very easily:

>> a = [0,0,0,0,0];
>> ida = find(a==max(a));
>> idx = randi(numel(ida))
idx =  4
>> a(ida(idx))
ans = 0

[Steven Lord]

Don't use idx as an index into a. Use it as an index into ida.

a = [1:100 0 0];
ida = find(a == min(a))
idx = randi(numel(ida))
fprintf("Element %d of a is %d.\n", idx, a(idx));
fprintf("Element %d of the vector %s is %d, corresponding to %d in a.\n", ...
    idx, mat2str(ida), ida(idx), a(ida(idx)))

The same idea holds when using max instead of min.

[Stephen23]

@Steven Lord: thank you for bringing that to my attention... that was actually my original intent, but got lost somewhere along the way. Fixed now.