From bug-octave-request at che dot utexas dot edu  Wed Dec 29 02:48:51 1993
Subject: bug in rank.m
From: hornik at neuro dot tuwien dot ac dot at (Kurt Hornik)
To: bug-octave at che dot utexas dot edu
Date: Wed, 29 Dec 93 09:48 MET

There is a bug in the 0.79 rank.m which causes rank not to work when
invoked with TWO arguments.  I enclose diffs and a fixed rank.m.
-kurt

************************************************************************
diff -u --recursive --new-file rank.m rank.m.orig 
--- rank.m      Fri Dec 24 08:24:57 1993
+++ rank.m.orig Fri Dec 24 08:24:04 1993
 at @ -1,6 +1,6 @@
 function retval = rank (A, tol)
 
-# usage: rank (a, tol)
+# usage: rand (a, tol)
 #
 # Return the rank of the matrix a.  The rank is taken to be the number
 # of singular values of a that are greater than tol.
 at @ -12,8 +12,8 @@
 # where eps is machine precision and sigma is the largest singular
 # value of a.
 
-  sigma = svd (A);
   if (nargin == 1)
+    sigma = svd (A);
     tolerance = max (size (A)) * sigma (1) * eps;
   elseif (nargin == 2)
     tolerance = tol;
************************************************************************

************************************************************************
function retval = rank (A, tol)

# usage: rank (a, tol)
#
# Return the rank of the matrix a.  The rank is taken to be the number
# of singular values of a that are greater than tol.
#
# If the second argument is omitted, it is taken to be
#
#   tol =  max (size (a)) * sigma (1) * eps;
#
# where eps is machine precision and sigma is the largest singular
# value of a.

  sigma = svd (A);
  if (nargin == 1)
    tolerance = max (size (A)) * sigma (1) * eps;
  elseif (nargin == 2)
    tolerance = tol;
  else
    error ("usage: rank (A)");
  endif
  retval = sum (sigma > tolerance);

endfunction