# MATLAB: Higher order polynomial regression

polynomialregression

I have to run a regression of order 5. My X matrix is
   102.1750    108.0515    102.1785    100.9413    102.6634
My Y matrix is
         0      5.4810      7.6267     24.7082      7.7284
Both X and Y are approxiately 20×1, I just wanted to give an idea how they look like.
I have tried the following:
1. Beta=pinv(X'*X)*(X'*Y);2. Beta=(X'*X)\(X'*Y);3. Beta=(X*Y);4. Beta=polyfit(X,Y,5);    Expected=polyval(Beta,X);
The results are very different. Additionally polyfit/polyval shows the following warning:"Warning: Polynomial is not unique; degree >= number of data points"
Any ideas or suggestions of what am I doing wrong or how or what else can I try? What is the correct way to do it?

Beta=polyfit(X,Y,5); Expected=polyval(Beta,X);