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Asked by Minu
on 7 Jun 2013

Hi

I want to find the second largest and minimum value in array? A=[1;10;15;30;40;50;100].I want to get the result as Second minimum value=10 and second largest value=50 Help me plz...

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Answer by Andrei Bobrov
on 7 Jun 2013

Edited by Andrei Bobrov
on 7 Jun 2013

Accepted answer

[ii,ii] = sort(A); out = A(ii([2,end-1]));

for your example (A) just:

out = A([2,end-1]);

more variant

A1 = unique(A); out = A1([2,end-1]);

Show 1 older comment

Jan Simon
on 7 Jun 2013

The sorting can be more expensive than searching the max twice:

[ignore, index] = max(A); A(index) = -Inf; % [EDITED], not +Inf! max2 = max(A);

In this method Walter's suggestions must be considered also.

Walter Roberson
on 7 Jun 2013

If the array is single precision or double precision, NaN is safer than Inf as there might *be* Inf in the array.

If the array is any of the other numeric data types, Inf will not exist and will be treated as the maximum numeric value for that datatype.

Jan Simon
on 7 Jun 2013

Ficed typo: Of course -Inf is needed instead of +Inf to mask an existing maximium.

@Walter: Exactly. While the original message "A=[1;10;15;30;40;50;100]" looks like the OP talks about a double vector with finite values, the another type of input or values must be considered.

Even if another value is -Inf, my method replies the *correct* result. But NaN is the better choice.

## 1 Comment

## Walter Roberson (view profile)

Direct link to this comment:http://www.mathworks.com/matlabcentral/answers/78278#comment_153446

What do you want to do if there are multiple instances of the maximum or minimum?