POLYVAL Evaluate Polynomial Fit at Selected Points

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