max and min values in an array

Question

Deep P 2016-12-12

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评论： dpb 2016-12-12

Hello,

I am trying to find positive and negative maximum and minimum in an array.

Lets say I have a Matrix A=[1 -2 5;3 7 -9,4 6 8] if I use max and min functions on A,I get max(A)=[4 7 8] and min(A)=[1 -2 -9]. Since I wanted one singe number I performed max and min operations again.

max(max(A))= 8 and min(min(A))=-9

My requirement here is to get both positive and negative maximum and positive and negative minimum. Is there any way to find that?

Thank you.

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the cyclist 2016-12-12

Your language is not very clear to me. By "maximum" and "minimum", are you talking about the magnitude? So, is the following correct?

Maximum (magnitude) positive = 8
Minimum (magnitude) positive = 1
Maximum (magnitude) negative = -9
Minimum (magnitude) positive = -2

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Answer 1

the cyclist 2016-12-12

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https://ww2.mathworks.cn/matlabcentral/answers/316588-max-and-min-values-in-an-array#answer_246922

编辑：the cyclist 2016-12-12

在 MATLAB Online 中打开

If what I said in my comment is correct, then do the following:

maxMagPos = max(A(A>0))
minMagPos = min(A(A>0))
maxMagNeg = min(A(A<0))
minMagNeg = max(A(A<0))

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the cyclist 2016-12-12

The best form of thanks is upvoting and/or accepting answers. This rewards the contributor, and points future users to good answers.

I suggest you open a new post for your second question, which is quite different in nature, not really related to this one.

dpb 2016-12-12

@OP If this is something you do more than once, then I'd suggest writing a little utility function that returns the values in a single call; either the four variables or an array depending on how your application most frequently would use the results.

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