Summing the even index elements of a 1D array

Question

Camden Nelson 2023-5-6

0
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https://ww2.mathworks.cn/matlabcentral/answers/1958919-summing-the-even-index-elements-of-a-1d-array

评论： Camden Nelson 2023-5-6

I am trying to write a recursive function that sums the elements in even indexed position of a 1D array, but am not sure how to do this. I have some of the code started below, but it is obvously incorrect:

function [out] = mySumEven(A)

n = length(A);

if n == 1

out = 'No numbers in even positions';

elseif n == 2

out = A(2);

else

out = A(2) + mySumEven(A(4:n));

end

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Answer 1

Atsushi Ueno 2023-5-6

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https://ww2.mathworks.cn/matlabcentral/answers/1958919-summing-the-even-index-elements-of-a-1d-array#answer_1230144

编辑：Atsushi Ueno 2023-5-6

在 MATLAB Online 中打开

mySumEven([1 2 3 4 5 6 7 8 9])
No numbers in even positions
ans = 20
function [out] = mySumEven(A)
n = length(A);
if n == 1
    disp('No numbers in even positions'); % out = 'No numbers in even positions';
    out = 0; % added
elseif n == 2
    out = A(2);
else
    out = A(2) + mySumEven(A(3:n)); % out = A(2) + mySumEven(A(4:n));
end
end

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Atsushi Ueno 2023-5-6

在 MATLAB Online 中打开

MATLAB can add numerical values and character vectors. The output is as numeric vector. It means every charactor code have been added by 1.

1 + [1 2 3 4]
ans = 1×4
     2     3     4     5
1 + 'No numbers in even positions'
ans = 1×28
    79   112    33   111   118   110    99   102   115   116    33   106   111    33   102   119   102   111    33   113   112   116   106   117   106   112   111   116
char(ans)
ans = 'Op!ovncfst!jo!fwfo!qptjujpot'