r3962 - trunk/bse

[stw svn gnome org]

Author: stw
Date: 2006-10-12 07:27:58 -0400 (Thu, 12 Oct 2006)
New Revision: 3962

Modified:
   trunk/bse/ChangeLog
   trunk/bse/bseiirfilter.c
Log:
Thu Oct 12 13:25:38 2006  Stefan Westerfeld  <stefan space twc de>

	* bseiirfilter.c: Added some comments.


Modified: trunk/bse/ChangeLog
===================================================================
--- trunk/bse/ChangeLog	2006-10-12 00:28:53 UTC (rev 3961)
+++ trunk/bse/ChangeLog	2006-10-12 11:27:58 UTC (rev 3962)
@@ -1,3 +1,7 @@
+Thu Oct 12 13:25:38 2006  Stefan Westerfeld  <stefan space twc de>
+
+	* bseiirfilter.c: Added some comments.
+
 Thu Oct 12 02:23:15 2006  Tim Janik  <timj gtk org>
 
 	* bseiirfilter.c: enlarged ARRSIZ so order 16 filters can be calculated.

Modified: trunk/bse/bseiirfilter.c
===================================================================
--- trunk/bse/bseiirfilter.c	2006-10-12 00:28:53 UTC (rev 3961)
+++ trunk/bse/bseiirfilter.c	2006-10-12 11:27:58 UTC (rev 3962)
@@ -1545,7 +1545,7 @@
 static double c = 0.0;
 static double cgam = 0.0;
 static double scale = 0.0;
-double fs = 1.0e4;
+double fs = 1.0e4;	      /* sampling frequency  -- stw */
 static double dbr = 0.5;
 static double dbd = -40.0;
 static double f1 = 1.5e3;
@@ -1579,7 +1579,7 @@
 static double sang = 0.0;
 static double bw = 0.0;
 static double ang = 0.0;
-double fnyq = 0.0;
+double fnyq = 0.0;	      /* nyquist frequency  -- stw */
 static double ai = 0.0;
 static double pn = 0.0;
 static double an = 0.0;
@@ -2065,7 +2065,7 @@
             }
         }
     }
-  if( kind == 3 )
+  if( kind == 3 )   /* elliptic filter -- stw */
     {
       nz = n/2;
       ellpj( u, 1.0-m, &sn1, &cn1, &dn1, &phi1 );
@@ -2472,6 +2472,10 @@
     {
       printf( "%2d %17.9E %17.9E\n", j, aa[j], pp[j] );
     }
+
+  /* I /think/ at this point the polynomial is factorized in 2nd order filters,
+   * so that it can be implemented without stability problems -- stw
+   */
   printf( "poles and zeros with corresponding quadratic factors\n" );
   for( j=0; j<zord; j++ )
     {