Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / signal-1.1.3 / idst.m

diff --git a/octave_packages/signal-1.1.3/idst.m b/octave_packages/signal-1.1.3/idst.m
new file mode 100644 (file)
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+++ b/octave_packages/signal-1.1.3/idst.m
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+## Author: Paul Kienzle <pkienzle@users.sf.net> (2006)
+## This program is granted to the public domain.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{y} =} idst (@var{x})
+## @deftypefnx {Function File} {@var{y} =} idst (@var{x}, @var{n})
+## Computes the inverse type I discrete sine transform of @var{y}.  If @var{n} is 
+## given, then @var{y} is padded or trimmed to length @var{n} before computing 
+## the transform.  If @var{y} is a matrix, compute the transform along the 
+## columns of the the matrix.
+## @seealso{dst}
+## @end deftypefn
+
+function x = idst (y, n)
+
+  if (nargin < 1 || nargin > 2)
+    print_usage;
+  endif
+
+  if nargin == 1,
+    n = size(y,1);
+    if n==1, n = size(y,2); end
+  end
+  x = dst(y, n) * 2/(n+1);
+
+endfunction
+
+%!test
+%! x = log(gausswin(32));
+%! assert(x, idst(dst(x)), 100*eps)