usage:  kaiser (n, beta)

Returns the filter coefficients of the n-point Kaiser window with
parameter beta.

For the definition of the Kaiser window, see A. V. Oppenheim &
R. W. Schafer, "Discrete-Time Signal Processing".

The continuous version of width n centered about x=0 is:

besseli(0, beta * sqrt(1-(2*x/n).^2))
k(x) =  -------------------------------------,  n/2 <= x <= n/2
besseli(0, beta)

See also: kaiserord