How can I get a variable that starts in t=0?

Question

Amelie 2023-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/1916245-how-can-i-get-a-variable-that-starts-in-t-0

评论： Amelie 2023-2-21

Dear all,

I am trying to get an index for the variable y that starts at 500 in t=0 and is carried forward from period t=1 onwards by multiplying the variable y with ins_urz. In other words, I am trying to set a starting value for the variable y of 500 in t=0, and then multiply it by ins_urz from period t=1 onwards, in order to use the result of the multiplication in the respective period to multiply it by the continuous elements of ins_urz.

for t=0:249

y(1,1)=500;

y(t+1,:)=y(t,1).*ins_urz(t+1,:);

end

Unfortunately, this has not worked so far, because I get the error message "Index in position 1 is invalid. Array indices must be positive integers or logical values" every time I try.

Can someone help me how to insert the index correctly into the codes?

Thanks a lot for your help!

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Answer 1

Torsten 2023-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/1916245-how-can-i-get-a-variable-that-starts-in-t-0#answer_1176430

在 MATLAB Online 中打开

y = cumprod([500;ins_urz])

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Torsten 2023-2-21

ins_urz is a (250,1) vector

Then the line of code will do what you want.

Amelie 2023-2-21

Thank you!

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Answer 2

Jan 2023-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/1916245-how-can-i-get-a-variable-that-starts-in-t-0#answer_1176440

编辑：Jan 2023-2-21

在 MATLAB Online 中打开

y(1, 1) = 500;  % Set initial value before the loop
for t = 1:249   % y(1, :) is defined already, so start at t=1, not t=0
   y(t+1, :) = y(t, 1) * ins_urz(t+1, :);
end