How to sum individual elements MATLAB -
suppose have row matrix [a1 a2 a3 a4 .. an]
, wish achieve each of following in matlab
1) 1+a1 2) 1+a1+a2 3) 1+a1+a2+a3 4) 1+a1+a2+a3+a4 .... 1+a1+a2+...+an
how shall them?
this purpose of cumsum
function. if a
vector containing elements [a1 a2 a3 .. an]
then
b = cumsum([1 a]);
contains terms searching for. possibility is
b = 1 + cumsum(a);
edit
if don't want use built-in function cumsum
, simpler way go for
loop:
% consider preallocation speed b = nan(numel(a),1); % assign first element b(1) = 1 + a(1); % loop = 2:numel(a) b(i) = b(i-1) + a(i); end
or, without preallocation:
b = 1 + a(1); = 2:numel(a) b(end+1) = b(end) + a(i); end
best,
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