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  (c) TransEra Corp, 2021
W_kaiser
Kaiser-Bessel window.
 
Loading        LOADSUB ALL FROM "BESMC.HTS"
or LOADSUB FROM "MATHLIB.HTS"
or LOADSUB W_kaiser FROM "MATHLIB.HTS"
 
Usage                REAL A(*),B(*)
REAL P
CALL W_kaiser(A(*),P,B(*))
 
Description                
W_kaiser multiplies the sequence in array A by a Kaiser-Bessel window function of parameter p and returns the product in array B. Array A is unmodified. P controls the width of the central portion of the window; it must be positive, and is usually between 4 and 9. If N is the number of elements in the array A and k is the position in the array B, the formula for the window function, wk, is
In the above formula, k ranges in value from 0 to N - 1. I0 is the modified cylindrical Bessel function of the first kind (see I0).
 
P is often expressed in Kaiser-Bessel window for N=128
terms of a radian frequency parameter, a, using the expression
 
Errors
W_kaiser causes an HTBasic error if its arguments are not of the types listed in the USAGE section, above, if p is negative or zero, or if B contains fewer elements than A.
 
 
 
 
 
Example
The section on the Fft subroutine contains an example of windowing using the W_kaiser routine.
 
See Also
I0, W_cosine, W_trapezoid