Hi, I have this function , can help me to vectorize it? thanks

 f = 0;

 for i = 1:n-1
    fprod = 1;
    for j = max (i-1,1) : min(i+1,n)
      fprod =  fprod * x(j)^3;
    end    
    f = f + fprod;
end

Answer 1

[Anthony Barone]

I think this will work.

% % % % % CREATE MASK FOR MATRIX MULTIPLICATION % % % % %
% each column computes the summation for 1 element of 'fprod'

% get probnlem size (i.e., numel(x)) 
nx = numel(x);

% reduce n if it is needlessly large.
n = min(nx+1,n);

% build upper half of mask
mask = true(max(nx,n-1),n-1);
mask = tril(mask);

% crop edge of upper half if needed
if nx > n-1
    mask = mask(1:end-(nx-n+1),:);
end

% add in lower half
mask = [mask;flipud(mask(1:end-1,:))];

% % % % %  MAIN MATRIX MULTIPLY % % % % % 

% compute fprod using the mask
fprod = x(:)*mask;

% sum fprod to get f
f = fprod*true(nx,1);