trouble with complicated loop

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Rock Rocky 2014-6-10

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评论： Rock Rocky 2014-6-10

Hello guys would u please help me in this question Let’s say the length of x=1000, I want to make a loop to calculate the value of A For I=1:x A=(1/I)*(x+1) %when the value of x=1 % when the value of x=2 the formula should be A=(1/I)*(x+2) + ((1/I-1)*(x+1)) % when the value of x=2 the formula should be A=((1/I)*(x+3)) + ((1/I-1)*(x+2) +(1/I-3)* (x+1))

. . . . and so on my question is how can I make this loop in a right way in order to calculate the value of A starting from x=1 till x=1000 thanks in advance

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Roger Wohlwend 2014-6-10

It seems that there are some typos in the formulas. Please make sure that the equations are correct - especially the one for x = 2;

Rock Rocky 2014-6-10

Ok let me put it in this way, I want to make a loop in order to add the current state with the previous state for example. M=1000; for i=1:M A=i*(x(i)); % this formula will be for M=1 but when M=2 the formula will be like this A=(i*(x(i))+((i-1)*(x(i-1)))and when M=3 the formula will be A=(i*(x(i))+((i-1)*(x(i-1)))+((i-2)*(x(i-2)) and so on till reach the maximum length of M which is 1000.

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Answer 1

David Sanchez 2014-6-10

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https://ww2.mathworks.cn/matlabcentral/answers/133492-trouble-with-complicated-loop#answer_140190

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% You are playing with two differet indeces: _i_ and _M_.
% You have to fix _i_ and then perform the summation:
x=rand(10,1); % sample data
M=4; % choose your own M
i = M + 1; % i has to be  greater than M. Otherwise an error will occur.
A = 0; % initialize the summation
for k=1:M 
    A= A + (i-(k-1))*x(i-(k-1));
end