Question

The output vector should look like :

a=[3 3 3 4 4 4 4 5 5 5 5 5]

What i have is:

pe=[1 5 9] and ne=[4 8 12] and co=[3 4 5]

pe describes the starting index and ne the ending index from each entry and co the value of this entry

I want do this without loop.
With Loop it should look like this:

  for i=1:3
     a(pe(i):ne(i))=co(i)
   end

Answer 1

One way to do this is to create an array of indices into co first, using cumsum

idxList = zeros(1,max(ne)); %# create an array with zeros
idxList(pe) = 1;            %# mark the start of a new index
idxList = cumsum(idxList);  %# now, idxList has 1's where we should
                            %# place the first element of co, etc
out = co(idxList);          %# and we're done.