Diff of /bitshift.m [000000] .. [67a5bd] Maximize Restore

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+## Copyright (C) 2000  Kai Habel
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{X} =} bitshift (@var{a},@var{k})
+## @deftypefnx {Function File} {@var{X} =} bitshift (@var{a},@var{k},@var{n})
+## return a @var{k} bit shift of @var{n}- digit unsigned
+## integers in @var{a}. A positive @var{k} leads to a left shift.
+## A negative value to a right shift. If @var{N} is omitted it defaults
+## to log2(bitmax)+1. 
+## @var{N} must be in range [1,log2(bitmax)+1] usually [1,33]
+## 
+##
+## @example
+## bitshift(eye(3),1))
+## @result{} 
+## @group
+## 2 0 0
+## 0 2 0
+## 0 0 2
+## @end group
+##
+## bitshift(10,[-2, -1, 0, 1, 2])
+## @result{} 2   5  10  20  40
+##
+## bitshift ([1, 10],2,[3,4])
+## @result{} 4  8
+##
+## @seealso{bitand,bitor,bitxor,bitset,bitget,bitcmp,bitmax}
+## @end deftypefn
+
+## Author:  Kai Habel <kai.habel@gmx.de>
+
+## Bug fixed by Paul Kienzle <pkienzle@kienzle.powernet.co.uk> 
+## log2(bitmax) must be rounded to nearest integer 
+
+function X = bitshift (A,k,n)
+  
+  if ((nargin < 2) | (nargin > 3))
+    usage ("bitshift(A,n,k)");
+  endif
+
+  if (nargin == 3)
+    n = fix (n);
+    if ( is_scalar(n) & (!is_scalar(k)) )
+      if (!is_scalar (A) & (size (A) != size (k)))
+        error ("size of A and k must match");
+      endif 
+      n = n .* ones (size (k));
+    elseif (!is_scalar (n)) & is_scalar (k)
+	  if (!is_scalar (A) & (size (A) != size (n)))
+        error ("size of A and n must match");
+      endif
+      k = fix (k) .* ones (size (n));
+    elseif (size (n) != size (k))
+      error ("size of n and k must match");
+    endif
+  else
+    n = round (log2 (bitmax) * ones (size (k)));
+  endif
+
+  if !(is_matrix (A)) || is_complex (A)
+    error ("first argument must be a real value");
+  else
+	X = fix (A .* pow2 (k));
+	X = bitand (X, pow2 (n) - 1);
+  endif
+
+endfunction