# HG changeset patch
# User jwe
# Date 1018388191 0
# Node ID abd8659eea11a59cbb621d4840b79946c7b016e0
# Parent  56db014d89803d4a59c0d6211984d69bd047642b
[project @ 2002-04-09 21:36:31 by jwe]

diff --git a/doc/interpreter/strings.txi b/doc/interpreter/strings.txi
--- a/doc/interpreter/strings.txi
+++ b/doc/interpreter/strings.txi
@@ -63,6 +63,9 @@
 @item \'
 Represents a literal single-quote character, @samp{'}.
 
+@item \0
+Represents the ``nul'' character, control-@, ASCII code 0.
+
 @item \a
 Represents the ``alert'' character, control-g, ASCII code 7.
 
diff --git a/scripts/ChangeLog b/scripts/ChangeLog
--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,3 +1,8 @@
+2002-04-09  Paul Kienzle <pkienzle@users.sf.net>
+
+	* scripts/freqz.m: Evaluate a specific range of frequencies
+	expressed in radians or Hz relative to a supplied sample rate.
+
 2002-04-04  Paul Kienzle <pkienzle@users.sf.net>
 
 	* signal/fftfilt.m: Filter columns if called with a matrix.
diff --git a/scripts/signal/freqz.m b/scripts/signal/freqz.m
--- a/scripts/signal/freqz.m
+++ b/scripts/signal/freqz.m
@@ -53,55 +53,104 @@
 ##
 ## For fastest computation, @var{n} should factor into a small number of
 ## small primes.
+##
+## @deftypefnx {Function File} {@var{h} =} freqz (@var{b}, @var{a}, @var{w})
+## Evaluate the response at the specific frequencies in the vector @var{w}.
+## The values for @var{w} are measured in radians.
+##
+## @deftypefnx {Function File} {[@dots{}] =} freqz (@dots{}, @var{Fs})
+## Return frequencies in Hz instead of radians assuming a sampling rate
+## @var{Fs}.  If you are evaluating the response at specific frequencies 
+## @var{w}, those frequencies should be requested in Hz rather than radians.
+##
 ## @end deftypefn
 
 ## Author: jwe ???
 
-function [h, w] = freqz(b,...)
+function [h, w] = freqz (b, a, n, region, Fs)
 
-  if (nargin == 1)
+  if (nargin < 1 || nargin > 5)
+    usage ("[h, w] = freqz (b, a, n [, \"whole\"] [, Fs])");
+  elseif (nargin == 1)
     ## Response of an FIR filter.
-    a = 1;
-    n = 512;
-    region = "half";
+    a = n = region = Fs = [];
   elseif (nargin == 2)
     ## Response of an IIR filter
-    a = va_arg();
-    n = 512;
-    region = "half";
+    n = region = Fs = [];
   elseif (nargin == 3)
-    a = va_arg();
-    n = va_arg();
-    region = "half";
+    region = Fs = [];
   elseif (nargin == 4)
-    a = va_arg();
-    n = va_arg();
-    region = va_arg();
+    Fs = [];
+    if (! isstr (region) && ! isempty (region))
+      Fs = region; 
+      region = [];
+    endif
+  endif
+
+  if (isempty (a)) 
+    a = 1; 
+  endif
+  if (isempty (n))
+    n = 512; 
+  endif
+  if (isempty (region))
+    if (isreal (b) && isreal (a))
+      region = "half";
+    else
+      region = "whole";
+    endif
+  endif
+  if (isempty (Fs)) 
+    if (nargout == 0) 
+      Fs = 2; 
+    else 
+      Fs = 2*pi; 
+    endif
   endif
 
-  la = length(a);
-  a = reshape(a,1,la);
-  lb = length(b);
-  b = reshape(b,1,lb);
+  la = length (a);
+  a = reshape (a, 1, la);
+  lb = length (b);
+  b = reshape (b, 1, lb);
+  k = max ([la, lb]);
 
-  k = max([la, lb]);
-
-  if (n >= k)
-    if (strcmp(region,"whole"))
-      h = fft(postpad(b,n)) ./ fft(postpad(a,n));
-      w = 2*pi*[0:(n-1)]/n;
+  if (! is_scalar (n))
+    if (nargin == 4) ## Fs was specified
+      w = 2*pi*n/Fs;
     else
-      h = fft(postpad(b,2*n)) ./ fft(postpad(a,2*n));
-      h = h(1:n);
-      w = pi*[0:(n-1)]/n;
+      w = n;
     endif
+    n = length (n);
+    extent = 0;
+  elseif (strcmp (region, "whole"))
+    w = 2 * pi * (0:n-1) / n;
+    extent = n;
   else
-    if (strcmp(region,"whole"))
-      w = 2*pi*[0:(n-1)]/n;
-    else
-      w = pi*[0:(n-1)]/n;
-    endif
-    h = polyval(postpad(b,k),exp(j*w)) ./ polyval(postpad(a,k),exp(j*w));
+    w = pi * (0:n-1) / n;
+    extent = 2 * n;
   endif
 
+  if (length (b) == 1)
+    if (length (a) == 1)
+      hb = b * ones (1, n);
+    else
+      hb = b;
+    endif
+  elseif (extent >= k) 
+    hb = fft (postpad (b, extent));
+    hb = hb(1:n);
+  else
+    hb = polyval (postpad (b, k), exp (j*w));
+  endif
+  if (length (a) == 1)
+    ha = a;
+  elseif (extent >= k)
+    ha = fft (postpad (a, extent));
+    ha = ha(1:n);
+  else
+    ha = polyval (postpad (a, k), exp (j*w));
+  endif
+  h = hb ./ ha;
+  w = Fs * w / (2*pi);
+
 endfunction
diff --git a/src/ChangeLog b/src/ChangeLog
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2002-04-09  Paul Kienzle <pkienzle@users.sf.net>
+
+	* utils.cc (do_string_escapes): Handle \0 too.
+	(undo_string_escape): Likewise.
+
 2002-04-04  John W. Eaton  <jwe@bevo.che.wisc.edu>
 
 	* toplev.cc (octave_config_info): Define struct member EXEEXT, not EXE.
diff --git a/src/utils.cc b/src/utils.cc
--- a/src/utils.cc
+++ b/src/utils.cc
@@ -382,6 +382,10 @@
 	{
 	  switch (s[++j])
 	    {
+	    case '0':
+	      retval[i] = '\0';
+	      break;
+
 	    case 'a':
 	      retval[i] = '\a';
 	      break;
@@ -474,6 +478,9 @@
 
   switch (c)
     {
+    case '\0':
+      return "\\0";
+
     case '\a':
       return "\\a";