How to implement a for loop over a specified range?

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Brian Aguilar 2016-2-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/270368-how-to-implement-a-for-loop-over-a-specified-range

评论： Brian Aguilar 2016-3-1

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

Outputs:

t: time vector ranging from Start to End with a sampling rate of fs
X: sum of sinusoids over the specified range

The code I am using for my outputs is:

t = linspace(Start,End,fs);
X=0;
for i=1:N
    X = X + A(i)*cos(2*pi*f(i)*t + phi(i)) + B(i);
end

I keep getting an error: Attempted to access B(2); index out of bounds because numel(B)=1. Need help fixing it.

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Walter Roberson 2016-2-27

We do not know how you initialized B, or what it is intended to mean.

Did you happen to compute B using the "/" operator?

Brian Aguilar 2016-3-1

编辑：Walter Roberson 2016-3-1

在 MATLAB Online 中打开

I got the same error for A too. Both B and A are N*1 matrix, where N is a integer, and positive. This is how I coded and initialized both A and B.

A = [N,1];
if ~all(isreal(A)) || ~all(A>0)
    error('Amplitude must be real and postive elements');
end
B = [N,1]; 
if  ~all(isreal(B))   
    error('B must be real and postive elements');
end

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Answer 1

Walter Roberson 2016-3-1

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https://ww2.mathworks.cn/matlabcentral/answers/270368-how-to-implement-a-for-loop-over-a-specified-range#answer_211759

在 MATLAB Online 中打开

The code you posted would result in A and B being scalars (length 1) if N is empty. If N was not empty, then A and B would only be of length 2 anyhow.

If you are trying to initialize A to be a vector of length N then you would use something like

A = zeros(N, 1);

... but then it would be all zero, which doesn't sound very meaningful.