--- a/doc/interpreter/numbers.txi	Mon Nov 04 16:21:14 2019 +0100
+++ b/doc/interpreter/numbers.txi	Mon Nov 04 08:09:37 2019 -0800
@@ -277,11 +277,10 @@
 separate matrix elements and rows.
 
 The maximum number of elements in a matrix is fixed when Octave is compiled.
-The allowable number can be queried with the function @code{sizemax}.  Note
-that other factors, such as the amount of memory available on your machine,
-may limit the maximum size of matrices to something smaller.
-
-@DOCSTRING(sizemax)
+If compiled with 64-bit index pointers the limit is @code{intmax ("int64")},
+otherwise it is @code{intmax ("int32")}.  Note that other factors, such as the
+amount of memory available on your machine, may limit the maximum size of
+matrices to something smaller.
 
 When you type a matrix or the name of a variable whose value is a
 matrix, Octave responds by printing the matrix in with neatly aligned

--- a/libinterp/corefcn/bitfcns.cc	Mon Nov 04 16:21:14 2019 +0100
+++ b/libinterp/corefcn/bitfcns.cc	Mon Nov 04 08:09:37 2019 -0800
@@ -946,27 +946,3 @@
 %!error <not defined for 'double' objects> intmin ("double")
 %!error <not defined for 'char' objects> intmin ("char")
 */
-
-DEFUN (sizemax, args, ,
-       doc: /* -*- texinfo -*-
-@deftypefn {} {} sizemax ()
-Return the largest value allowed for the size of an array.
-
-If Octave is compiled with 64-bit indexing, the result is of class int64,
-otherwise it is of class int32.  The maximum array size is slightly
-smaller than the maximum value allowable for the relevant class as reported
-by @code{intmax}.
-@seealso{intmax}
-@end deftypefn */)
-{
-  if (args.length () != 0)
-    print_usage ();
-
-  return octave_value (octave_int<octave_idx_type> (dim_vector::dim_max ()));
-}
-
-/*
-%!assert (sizemax () >= (intmax ("int32") - 1))
-
-%!error sizemax (0)
-*/

--- a/liboctave/array/dim-vector.cc	Mon Nov 04 16:21:14 2019 +0100
+++ b/liboctave/array/dim-vector.cc	Mon Nov 04 08:09:37 2019 -0800
@@ -39,6 +39,7 @@
   return zv.rep;
 }
 
+// FIXME: DEPRECATED, remove in version 8.
 // The maximum allowed value for a dimension extent.  This will normally be a
 // tiny bit off the maximum value of octave_idx_type.
 // Currently 1 is subtracted to allow safe conversion of any 2D Array into
@@ -102,7 +103,7 @@
 octave_idx_type
 dim_vector::safe_numel (void) const
 {
-  octave_idx_type idx_max = dim_max ();
+  octave_idx_type idx_max = std::numeric_limits<octave_idx_type>::max ();
   octave_idx_type n = 1;
   int n_dims = ndims ();
 

--- a/liboctave/array/dim-vector.h	Mon Nov 04 16:21:14 2019 +0100
+++ b/liboctave/array/dim-vector.h	Mon Nov 04 08:09:37 2019 -0800
@@ -261,6 +261,7 @@
 
 public:
 
+  OCTAVE_DEPRECATED (6, "dim_vector::dim_max () is deprecated; any uses should be removed")
   static octave_idx_type dim_max (void);
 
   explicit dim_vector (void) : rep (nil_rep ())

--- a/scripts/deprecated/module.mk	Mon Nov 04 16:21:14 2019 +0100
+++ b/scripts/deprecated/module.mk	Mon Nov 04 08:09:37 2019 -0800
@@ -2,7 +2,8 @@
 
 %canon_reldir%_FCN_FILES = \
   %reldir%/output_max_field_width.m \
-  %reldir%/runtests.m
+  %reldir%/runtests.m \
+  %reldir%/sizemax.m
 
 %canon_reldir%dir = $(fcnfiledir)/deprecated
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/deprecated/sizemax.m	Mon Nov 04 08:09:37 2019 -0800
@@ -0,0 +1,58 @@
+## Copyright (C) 2019 Rik Wehbring
+##
+## This file is part of Octave.
+##
+## Octave 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 3 of the License, or
+## (at your option) any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <https://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {} {} sizemax ()
+##
+## @code{sizemax} is deprecated and will be removed in Octave version 8.
+##
+## Return the largest value allowed for the size of an array.
+## 
+## If Octave is compiled with 64-bit indexing, the result is of class int64,
+## otherwise it is of class int32.  The maximum array size is slightly smaller
+## than the maximum value allowable for the relevant class as reported by
+## @code{intmax}.
+## @seealso{intmax}
+## @end deftypefn
+
+## FIXME: DEPRECATED: Remove in version 8.
+
+function retval = sizemax (varargin)
+
+  persistent warned = false;
+  if (! warned)
+    warned = true;
+    warning ("Octave:deprecated-function",
+             "sizemax is obsolete and will be removed from a future version of Octave\n");
+  endif
+
+  if (nargin != 0)
+    print_usage ();
+  endif
+
+  if (__have_feature__ ("ENABLE_64"))
+    retval = intmax ("int64") - 1;
+  else
+    retval = intmax ("int32") - 1;
+  endif
+
+endfunction
+
+
+%!assert (sizemax () >= (intmax ("int32") - 1))
+%!error sizemax (0)

--- a/scripts/sparse/private/__sprand__.m	Mon Nov 04 16:21:14 2019 +0100
+++ b/scripts/sparse/private/__sprand__.m	Mon Nov 04 08:09:37 2019 -0800
@@ -56,7 +56,13 @@
     if (nargin == 5)
       mn = m*n;
       k = round (d*mn);
-      if (mn > sizemax ())
+      ## FIXME: randperm() should be fixed to handle large values
+      if (__have_feature__ ("ENABLE_64"))
+        max_numel = intmax ("int64");
+      else
+        max_numel = intmax ("int32");
+      endif
+      if (mn > max_numel)
         ## randperm will overflow, so use alternative methods
 
         idx = unique (fix (rand (1.01*k, 1) * mn)) + 1;