trying to fit x1 and y1 and in result want fitted value but for that this error is coming ? How can I improve my result?

In polyfit at 76 
Warning: Polynomial is badly conditioned. Add points with distinct X values, reduce
the degree of the polynomial, or try centering and scaling as described in HELP
POLYFIT.

Answer 1

[Image Analyst]

When you get that error, you must use the S and mu arguments. See the help for polyfit, as the error message directed you to.

[RS]

what is meaning of S and mu arguments

[Image Analyst]

They do centering and scaling so your numbers don't have such a huge range, which limits your accuracy.

[RS]

     again same type of error coming how can I make good results warning(message('MATLAB:polyfit:RepeatedPoints'));

In polyfit at 74 Warning: Polynomial is badly conditioned. Add points with distinct X values or reduce the degree of the polynomial.

I am using this 
[p S mu]= polyfit(x1(1:xxx),y2,3);