polyval returns the value of a polynomial of degree n evaluated at x. y = polyval(p,x,[],mu) or [y,delta] = polyval(p,x,S,mu) use x^=(x−μ1)/μ2 in place of x. In this equation, μ1=mean(x)and μ2=std(x). The centering and scaling parameters mu = [μ1,μ2] is optional y= polyval(p,x) [y,delta] = polyval(p,x,S) p: vector of length n+1 whose elements are the coefficients in descending powers of the polynomial to be evaluated. x: -can be a matrix or a vector. In either case, polyval evaluates p at each element of x. delta: -is an estimate of the standard deviation of the error in predicting a future observation at x by p(x).