Maybe a colon operator

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Manila Gomes
Manila Gomes 2017-11-28
编辑： Jan 2017-11-28
It is possible write this for in a more fast code (maybe colon)?
for i = 2 : n-1
A(i) = A(i-1)+A(i+1);
end

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采纳的回答

Birdman
Birdman 2017-11-28
Vectorizing is possible and better. One approach:
A=randi([1 10],1,10)
n=numel(A);
i=2:n-1;
A(i)=A(i-1)+A(i+1)

更多回答（1 个）

KSSV
KSSV 2017-11-28
编辑：KSSV 2017-11-28
N = 10 ;
A = rand(N,1) ;
i = 2:N-1 ;
B = A(i-1)+A(i+1);
  1 个评论
Jan
Jan 2017-11-28
编辑：Jan 2017-11-28
Note: If N is huge, creating the index vectors explicitly is slower than:
N = 1e7;
A = rand(N, 1) ;
B = A(1:(N-2)) + A(3:N);
Here Matlab checks only for the 4 given indices, if they are inside the valid range, while for
i = 2:N-1 ;
B = A(i-1) + A(i+1);
Matlab requires 2e7-4 boundary checks.

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