Error using / Matrix dimensions must agree and Forward Linear Prediction
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I'm trying to predict the future values of my data sample with the following code:
for n = 1:size(t,1)
if n>=3
X = [Ia(n-1,1) Ia(n-2,1) ; Ia(n-2,1) Ia(n-3,1)];
p = [Ia(n,1) ; Ia(n-1,1)];
C = X/p;
Ia_future(n,1) = C(1,1)*Ia(n,1)+C(2,1)*Ia(n-1,1)
erro(n,1)=Ia(n)+Ia_future(n,1)
end
end
Where Ia is the phase current a and t is the period, both have a length equal to 2400.
It ends up giving the following error in the operation C = X/p (Error using / Matrix dimensions must agree.)
Basically the operations I'm trying to reproduce are the ones in the equations below:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/826575/image.jpeg)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/826580/image.jpeg)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/826585/image.jpeg)
I need to find the error of each predicted value. However, it seems that what I am doing is not right.
x = Ia
fp = error
x^ = Ia_future
The matrix is 2x2 because the order of the prediction I want to get is 2. So I get a future value every 2 values, n>=3.
5 个评论
Walter Roberson
2021-12-8
Okay, but even if I do p/X it accuses the same error.
It is not clear what your X is here?
Note that, by definition,
A/B = (B'\A')'
So A\p is not the same as p/A -- you would need (p' / A')'
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