How can i find the position of same elements in matlab......

For Example :

    x=[1 1 1 2 2 3 3 5 5 5 7 7 7]

result =

     1     1     3
     2     4     5
     3     6     7
     5     8    10
     7    11    13

Regards.......

 I try something like this, ('works')but is really slow 
    ind=unique(x)
    for i = 1 : length(ind);
    [z] =find(x==ind(i))
    limit(i,:)=[z(1) z(end)]
    end

Answer 1

[Andrei Bobrov]

[a,b1] = unique(x,'first');
[a,b2] = unique(x,'last');
result = [a(:),b1,b2];

or

ii = [find([true;diff(x(:))~=0]);numel(x)+1];
result=[x(ii(1:end-1))',ii(1:end-1),ii(2:end)-1];

[Javier]

ULTRA SUPER FAST, THANKS ANDREI BOBROV...............

Answer 2

[Walter Roberson]

hint: look at find() in conjunction with diff(x)

[Javier]

Thanks Walter,