How to create an Octave function that evaluate the sum of pairs of numbers in the vector?

Notice that the number of times each element gets added to produce the final result comes from Pascals triangle itself, so, e.g., for the vector [a b c d] the result will be a+3b+3c+d. So create a vector of entries in Pascals triangle and multiply and add with the original vector v.

I only have access to Matlab, Octave may not have all these functions.

This is a one-liner diag(fliplr(pascal(numel(v)))).'*v(:).

Or a looping version

s = 0; for i = 0:numel(v)-1 s = s+nchoosek(numel(v)-1,i)*v(i+1); end s 

Simplest thing I can think of is:

while length(x) > 0 disp(x) x = x(1:end-1) + x(2:end); end 

or did I misunderstand the question?

Here is the version for both MATLAB and Octave:

function y = lastnum(v) while 1 if length(v) == 2 y = sum(v) break; end # disp(v); # if you want to print the progress vt = []; for k = 1:(length(v)-1) vt(end+1) = sum(v(k:(k+1))); end v = vt; end end