MATLAB: Elements processing in array

array

If array A=[ b c ], I want to create value [b+c -b+c b-c -b-c]
or A=[ b c d ], then output should be [ b+c+d b+c-d b-c+d b-c-d -b+c+d -b+c-d -b-c+d -b-c-d ]
Is there any function in MATLAB that can easily solve my problem ? Thanks.

Best Answer

You basically want the sum of the n-ary product of the +/- sets of each element of your array. That can be done easily with ndgrid:
A = [1 3 8 2];  %demo data;
sets = num2cell([A; -A], 1);  %split into sets of +/- values
nprod = cell(1, numel(A));  %create destination for n-ary product
[nprod{:}] = ndgrid(sets{:});  %calculate n-ary product
nprod = reshape(cat(numel(A)+1, nprod{:}), [], numel(A)); %concatenate into one matrix and reshape. Each row is one of the possible combination
sumnprod = sum(nprod, 2)  %wanted result
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