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

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Ararat Cetinkaya 2020-5-17

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https://ww2.mathworks.cn/matlabcentral/answers/526116-if-all-elemets-of-a-array-equal-which-array-will-be-choose-by-max-function

编辑： Stephen23 2020-5-18

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 ?

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Answer 1

Stephen23 2020-5-17

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编辑：Stephen23 2020-5-18

在 MATLAB Online 中打开

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

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Steven Lord 2020-5-17

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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)))