00   /**********************************************************************
01   Copyright (c) 2014 Mark C. Erickson
02  
03   Permission is hereby granted, free of charge, to any person obtaining
04   a copy of this software and associated documentation files (the
05   "Software"), to deal in the Software without restriction, including
06   without limitation the rights to use, copy, modify, merge, publish,
07   distribute, sublicense, and/or sell copies of the Software, and to
08   permit persons to whom the Software is furnished to do so, subject to
09   the following conditions:
10  
11   The above copyright notice and this permission notice shall be included
12   in all copies or substantial portions of the Software.
13  
14   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
17   IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
18   CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
19   TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
20   SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21   **********************************************************************/
22  

     Disclaimer...

23   desc:EQ, Notch 2nd-Order, v1.0.1
24  
25   slider1:2000<20,20000,1>Cutoff [Hz]
26  
27   @init
28   x=0;
29   x1=0;
30   x2=0;
31   y=0;
32   y1=0;
33   y2=0;
34   q=3.16;
35  
36   @slider
37   slider1 > 19 ? (
38   w = 2.0 * $pi * slider1 / srate;
39   beta = 0.5 * (( 1.0 - tan(w/2.0/q) ) / ( 1.0 + tan(w/2.0/q) ));
40   gamma = ( 0.5 + beta ) * cos(w);
41   alpha = ( 0.5 + beta ) / 2.0;
42   )
43  
44   @sample
45   x = spl0;
46   y = 2.0 * ( alpha * x - gamma * x1 + alpha* x2 + gamma * y1 - beta * y2 );
47   x2 = x1;
48   x1 = x;
49   y2 = y1;
50   y1 = y;
51   spl0 = y;
52