How to find second largest value and its index in an array?

Hello everyone, I am trying to find the second largest value and its index in an array given by

A = [11,15,16,99,87]

Any help in this regard will be highly appreciated.

Answer 1

[Matt J]

A = [11,15,16,99,87];

[mx,ind]=maxk(A,2)

mx = 1×2

99 87

ind = 1×2

4 5

secondMax=mx(2)

secondMax = 87

index=ind(2)

index = 5

[Matt J]

Or, if ties are not allowed

A = [11,15,16,99,99];

[u,i]=unique(A);

secondMax=u(end-1)

secondMax = 16

index=i(end-1)

index = 3

Answer 2

[Image Analyst]

charu, did you try sorting and using find()? We also need to know your definition of "second largest".

% What is the second largest in this vector: 99 or 87?
A = [11,15,16,99,87, 99, 87]
% Assume it's 87, then to find all locations where 87 occurs:
sortedA = sort(unique(A), 'descend')
indexes = find(A == sortedA(2))

You get

A =

11 15 16 99 87 99 87

sortedA =

99 87 16 15 11

indexes =

5 7