--- a/scripts/help/__unimplemented__.m	Wed Jun 16 06:31:15 2021 -0700
+++ b/scripts/help/__unimplemented__.m	Wed Jun 16 11:25:15 2021 -0400
@@ -980,7 +980,6 @@
   "maxflow",
   "MaximizeCommandWindow",
   "maxk",
-  "maxNumCompThreads",
   "memmapfile",
   "memoize",
   "MemoizedFunction",

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/legacy/maxNumCompThreads.m	Wed Jun 16 11:25:15 2021 -0400
@@ -0,0 +1,70 @@
+########################################################################
+##
+## Copyright (C) 2021 The Octave Project Developers
+##
+## See the file COPYRIGHT.md in the top-level directory of this
+## distribution or <https://octave.org/copyright/>.
+##
+## 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 {} {@var{n} = } maxNumCompThreads ()
+## @deftypefnx {} {@var{old} =} maxNumCompThreads (@var{n})
+## @deftypefnx {} {@var{old} =} maxNumCompThreads ("automatic")
+## This function is provided for Matlab compatibility only.  It uses the
+## @code{nproc} function to return the number of available processors.
+## It may also be called with an argument to set the number of
+## computational threads but that setting has no effect.
+## @seealso{nproc}
+## @end deftypefn
+
+function retval = maxNumCompThreads (arg)
+
+  persistent nthreads = nproc ();
+
+  if (nargin > 1)
+    print_usage ();
+  endif
+
+  retval = nthreads;
+
+  if (nargin == 1)
+    if (isnumeric (arg) && isscalar (arg) && arg == fix (arg)
+        && arg > 0 && isfinite (arg))
+      ## FIXME: Should there be an upper limit?
+      nthreads = arg;
+      warning ("Octave:maxNumCompThreads:no-effect",
+               "maxNumCompThreads: setting number of threads has no effect");
+    elseif (ischar (arg) && strcmpi (arg, "automatic"))
+      nthreads = nproc ();
+    endif
+  endif
+
+endfunction
+
+%!test
+%! maxNumCompThreads ("automatic");
+%! assert (maxNumCompThreads (), nproc ());
+
+%!test
+%! warning ("off", "Octave:maxNumCompThreads:no-effect", "local");
+%! maxNumCompThreads (4);
+%! assert (maxNumCompThreads ("automatic"), 4);
+
+%!error <called with too many inputs> maxNumCompThreads (1, 2);

--- a/scripts/legacy/module.mk	Wed Jun 16 06:31:15 2021 -0700
+++ b/scripts/legacy/module.mk	Wed Jun 16 11:25:15 2021 -0400
@@ -9,6 +9,7 @@
   %reldir%/isdir.m \
   %reldir%/isequalwithequalnans.m \
   %reldir%/isstr.m \
+  %reldir%/maxNumCompThreads.m \
   %reldir%/setstr.m \
   %reldir%/strmatch.m \
   %reldir%/strread.m \