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Section: Optimization and Curve Fitting
The polyval routine has the following syntax 
y = polyval(p,x)
 where p is a vector of polynomial coefficients, in decreasing degree (as generated by polyfit, for example). If x is a matrix, the polynomial is evaluated in the matrix sense (in which case x must be square). 
The polynomial is evaluated using a recursion method. If the polynomial is
![\[ p(x) = p_1 x^n + p_2 x^{n-1} + \dots + p_n x + p_{n+1} \]](form_10.png) 
then the calculation is performed as
![\[ p(x) = ((p_1) x + p_2) x + p_3 \]](form_12.png) 
Here is a plot of x^3 generated using polyval
--> p = [1 0 0 0] p = 1 0 0 0 --> x = linspace(-1,1); --> y = polyval(p,x); --> plot(x,y,'r-')
Here is the resulting plot
