Re: [Audacity-nyquist] extreme newbie question about abs function

[David S. <dav...@vc...>]

Thanks Steven, s-max does work, but only on mono signals, even if
I include a (if (arrayp s)...) check, as below (which I have
commented out). Below that is the Nyquist error msg, which I don't
understand. David

;nyquist plug-in
;version 1
;type process
;name "Rectifier..."
;action "Rectifying audio..."
;info "Code by Steven Jones\nReleased under terms of GPL"

;control rectify "Rectify" int "0=half 1=full" 1 0 1

; Rectifier compiled by David R. Sky,
; code by Steven Jones
; March 29, 2005
; Released under terms of the GNU Public License
; http://www.opensource.org/licenses/gpl-license.php

; Return only the positive half cycles of signal
(defun pos (signal)
(s-max signal 0))

; Return only the negative half-cycles of signal
; AND invert them.
(defun neg (signal)
(pos (scale -1 signal)))

(defun my-abs (signal rectify)
(if (= rectify 1)
    (sum (pos s) (neg s))
(pos s)))

; checking for stereo signal
; (if (arrayp s)
; (vector (my-abs (aref s 0) rectify)
; (my-abs (aref s 1) rectify))
(my-abs s rectify)
; )

error: bad argument type - 0
Function: #<Subr-LENGTH: #12cbb40>
Arguments:
  0
Function: #<FSubr-COND: #12cb570>
Arguments:
  ((/= N (LENGTH S2)) (ERROR "unequal number of channels in max"))
Function: #<FSubr-LET*: #12cb430>
Arguments:
  ((N (LENGTH S1)) (P (MAKE-ARRAY N)))
  (COND ((/= N (LENGTH S2)) (ERROR "unequal number of channels in
max")))   (DOTIMES (I N) (SETF (AREF P I) (S-MAX (AREF S1 I) (AREF
S2 I))))   P
Function: #<Closure-NYQ:MAX-OF-ARRAYS: #12fe068>
Arguments:
  #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
  0
Function: #<FSubr-COND: #12cb570>
Arguments:
  ((ARRAYP S1) (NYQ:MAX-OF-ARRAYS S1 S2))
  (T (NYQ:MAX-2-SOUNDS S1 S2))
Function: #<Closure-S-MAX: #12fe548>
Arguments:
  #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
  0
Function: #<Closure-POS: #130be80>
Arguments:
  #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
Function: #<FSubr-IF: #12cb3f0>
Arguments:
  (= RECTIFY 1)
  (SUM (POS S) (NEG S))
  (POS S)
Function: #<Closure-MY-ABS: #130bb00>
Arguments:
  #(#<Sound: #7cb2390> #<Sound: #7cb2618>)
  1
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