plot(flip(AdjClose))y = flip(AdjClose)x = 1:503;polyfit(y,x,0)x is a 503*1 double and y is a 1*503 double. I wonder how can I make them the same size?
MATLAB: Error using Polyfit, X and Y vectors must be the same size
errorpolyfit
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Because the syntax should be
polyfit(x,y,N)
and not
polyfit(y,x,N)
Here is some code that illustrates the fix:
x = 1:503;
y = 250 + 0.02*x + 0.005*x.^2 + 0.2*rand(1,503).*x;
figure polyfit(y,x,0); coef1 = polyfit(x,y,0); y1 = polyval(coef1,x); hold on plot(x,y,'.'); plot(x,y1); polyfit(x,y,1); coef2 = polyfit(x,y,1); y2 = polyval(coef2,x); plot(x,y2); polyfit(y,x,2); coef3 = polyfit(x,y,2); y3 = polyval(coef3,x); plot(x,y3);
p = polyfit(temp,carbonSteel,3);y = polyval(p,carbonSteel);What did you build? A model, that predicts carbonsteel, as a function of temp. So temp is the INDEPENDENT variable.
Now, you want to predict the dependent variable, as as a function of temp. So you need to do this:
y = polyval(p,temp);plot(temp,carbonsteel,'bo',temp,y,'r-')
What you did, as you did it, makes no sense in context of the model you built..
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