Apply a digital filter (direct form II transposed): Difference between revisions
Apply a digital filter (direct form II transposed) (view source)
Revision as of 20:45, 30 August 2020
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{{trans|C}} Strangely, C was more informative than Common Lisp in helping figure out what was going on here.
<lang racket>
(define a (vector 1.00000000E0 -2.77555756E-16 3.33333333E-01 -1.85037171E-17))
(define b (vector 0.16666667E0 0.50000000E0 0.50000000E0 0.16666667E0))
(define s (vector -0.917843918645 0.141984778794 1.20536903482 0.190286794412 -0.662370894973
-1.00700480494 -0.404707073677 0.800482325044 0.743500089861 1.01090520172
0.741527555207 0.277841675195 0.400833448236 -0.2085993586 -0.172842103641
-0.134316096293 0.0259303398477 0.490105989562 0.549391221511 0.9047198589))
(define (filter-signal-direct-form-ii-transposed coeff1 coeff2 signal)
(define signal-size (vector-length signal))
(define filtered-signal (make-vector signal-size 0))
(for ((i signal-size))
(vector-set! filtered-signal
i
(/ (for/fold ((s (for/fold ((s 0)) ((j (vector-length coeff2)) #:when (>= i j))
(+ s (* (vector-ref coeff2 j) (vector-ref signal (- i j)))))))
((j (vector-length coeff1)) #:when (>= i j))
(- s (* (vector-ref coeff1 j) (vector-ref filtered-signal (- i j)))))
(vector-ref coeff1 0))))
filtered-signal)
(filter-signal-direct-form-ii-transposed a b s)</lang>
{{out}}
<pre>'#(-0.15297398950031305
-0.4352578290502175
-0.13604339698849033
0.6975033265479628
0.6564446924690288
-0.4354824532561056
-1.0892394611529292
-0.5376765495627545
0.5170499923132141
1.0522497471553531
0.9618543003736449
0.6956900940096049
0.42435629509553213
0.19626223182178917
-0.027835124463393326
-0.21172191545011781
-0.17474556222276072
0.06925840890119488
0.3854458743074388
0.6517708388193052)</pre>
=={{header|Raku}}==
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