## POLYVAL Evaluate Polynomial Fit at Selected Points

Section: Optimization and Curve Fitting

### Usage

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).

### Function Internals

The polynomial is evaluated using a recursion method. If the polynomial is

then the calculation is performed as

### Example

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