Finding maximum value of y at some x

I have a vector y=[6 8 10 9 11 31] x=[1 2 3 4 5 6] how to find at what x the first maximum value of y occured and the second maxima

Answer 1

[Roger Stafford]

   [~,p] = sort(y,’descend’);
   x2 = x(p(1:2)); % <-- x values at first and second maxima of y

Answer 2

[KSSV]

doc findpeaks()..... Check the link for further explanation: http://in.mathworks.com/matlabcentral/answers/44227-finding-local-minimums-maximums-for-a-set-of-data

Answer 3

[Andrei Bobrov]

y=[6 8 11 10 31 9 11 31]
x=[3 9 4 1 23 3 2 7]

[a,~,c] = unique(y);
ii = accumarray(c(:),(1:numel(c))',[],@(x){x});
idx = ii([end,end-1]);
out = cellfun(@(a)x(a),idx,'un',0)