--- a/NEWS	Wed Dec 16 16:47:18 2015 -0800
+++ b/NEWS	Thu Dec 17 16:04:13 2015 +0100
@@ -80,6 +80,8 @@
       bitmax               | flintmax
       mahalanobis          | mahal in Octave-Forge statistics pkg
       md5sum               | hash
+      sleep                | pause
+      usleep               | pause
       wavread              | audioread
       wavwrite             | audiowrite
 

--- a/doc/interpreter/system.txi	Wed Dec 16 16:47:18 2015 -0800
+++ b/doc/interpreter/system.txi	Thu Dec 17 16:04:13 2015 +0100
@@ -129,10 +129,6 @@
 
 @DOCSTRING(pause)
 
-@DOCSTRING(sleep)
-
-@DOCSTRING(usleep)
-
 @DOCSTRING(datenum)
 
 @DOCSTRING(datestr)

--- a/libinterp/corefcn/cutils.c	Wed Dec 16 16:47:18 2015 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,55 +0,0 @@
-/*
-
-Copyright (C) 1999-2015 John W. Eaton
-
-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
-<http://www.gnu.org/licenses/>.
-
-*/
-
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
-
-#include <stdio.h>
-#include <time.h>
-
-#include <sys/types.h>
-#include <unistd.h>
-
-#include "cutils.h"
-
-void
-octave_sleep (unsigned int seconds)
-{
-  sleep (seconds);
-}
-
-void
-octave_usleep (unsigned int useconds)
-{
-  struct timespec delay;
-  struct timespec remaining;
-
-  unsigned int sec = useconds / 1000000;
-  unsigned int usec = useconds % 1000000;
-
-  delay.tv_sec = sec;
-  delay.tv_nsec = usec * 1000;
-
-  nanosleep (&delay, &remaining);
-}
-

--- a/libinterp/corefcn/cutils.h	Wed Dec 16 16:47:18 2015 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,40 +0,0 @@
-/*
-
-Copyright (C) 2012-2015 John W. Eaton
-
-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
-<http://www.gnu.org/licenses/>.
-
-*/
-
-#if ! defined (octave_cutils_h)
-#define octave_cutils_h 1
-
-#include <stdarg.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-OCTINTERP_API void octave_sleep (unsigned int seconds);
-
-OCTINTERP_API void octave_usleep (unsigned int useconds);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif

--- a/libinterp/corefcn/data.cc	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/data.cc	Thu Dec 17 16:04:13 2015 +0100
@@ -6172,7 +6172,7 @@
 \n\
 @example\n\
 @group\n\
-id = tic; sleep (5); toc (id)\n\
+id = tic; pause (5); toc (id)\n\
       @result{} 5.0010\n\
 @end group\n\
 @end example\n\

--- a/libinterp/corefcn/graphics.cc	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/graphics.cc	Thu Dec 17 16:04:13 2015 +0100
@@ -43,7 +43,6 @@
 #include "singleton-cleanup.h"
 
 #include "builtins.h"
-#include "cutils.h"
 #include "defun.h"
 #include "display.h"
 #include "error.h"
@@ -58,6 +57,7 @@
 #include "toplev.h"
 #include "txt-eng-ft.h"
 #include "unwind-prot.h"
+#include "utils.h"
 #include "octave-default-image.h"
 
 // forward declarations
@@ -10983,7 +10983,7 @@
               go.get_toolkit ().print_figure (go, term, file, mono,
                                               debug_file);
 
-              Fsleep (octave_value (0.05));
+              octave_sleep (0.05); // FIXME: really needed?
 
               gh_manager::lock ();
             }
@@ -11612,7 +11612,7 @@
             break;
         }
 
-      octave_usleep (100000);
+      octave_sleep (0.1); // FIXME: really needed?
 
       OCTAVE_QUIT;
 

--- a/libinterp/corefcn/matherr.c	Wed Dec 16 16:47:18 2015 -0800
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,53 +0,0 @@
-/*
-
-Copyright (C) 1997-2015 John W. Eaton
-
-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
-<http://www.gnu.org/licenses/>.
-
-*/
-
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
-
-#if defined (EXCEPTION_IN_MATH)
-
-#include "lo-math.h"
-
-int
-matherr (struct exception *x)
-{
-  /* Possibly print our own message someday.  Should probably be
-     user-switchable. */
-
-  switch (x->type)
-    {
-    case DOMAIN:
-    case SING:
-    case OVERFLOW:
-    case UNDERFLOW:
-    case TLOSS:
-    case PLOSS:
-    default:
-      break;
-    }
-
-  /* But don't print the system message. */
-
-  return 1;
-}
-#endif

--- a/libinterp/corefcn/module.mk	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/module.mk	Thu Dec 17 16:04:13 2015 +0100
@@ -28,7 +28,6 @@
   libinterp/corefcn/c-file-ptr-stream.h \
   libinterp/corefcn/cdisplay.h \
   libinterp/corefcn/comment-list.h \
-  libinterp/corefcn/cutils.h \
   libinterp/corefcn/data.h \
   libinterp/corefcn/debug.h \
   libinterp/corefcn/defun-dld.h \
@@ -110,8 +109,6 @@
   libinterp/corefcn/oct-tex-parser.yy
 
 C_COREFCN_SRC = \
-  libinterp/corefcn/cutils.c \
-  libinterp/corefcn/matherr.c \
   libinterp/corefcn/siglist.c
 
 COREFCN_SRC = \

--- a/libinterp/corefcn/syscalls.cc	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/syscalls.cc	Thu Dec 17 16:04:13 2015 +0100
@@ -218,7 +218,7 @@
   if (ischar (s))\n\
     fputs (stdout, s);\n\
   elseif (errno () == EAGAIN)\n\
-    sleep (0.1);\n\
+    pause (0.1);\n\
     fclear (out);\n\
   else\n\
     done = true;\n\
@@ -317,7 +317,7 @@
 %!       str{idx} = s;
 %!     elseif (errno () == EAGAIN)
 %!       fclear (out);
-%!       sleep (0.1);
+%!       pause (0.1);
 %!       if (++errs == 100)
 %!         done = true;
 %!       endif
@@ -348,7 +348,7 @@
 %!       str{idx} = s;
 %!     elseif (errno () == EAGAIN)
 %!       fclear (out);
-%!       sleep (0.1);
+%!       pause (0.1);
 %!       if (++errs == 100)
 %!         done = true;
 %!       endif

--- a/libinterp/corefcn/sysdep.cc	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/sysdep.cc	Thu Dec 17 16:04:13 2015 +0100
@@ -742,22 +742,31 @@
 @deftypefnx {} {} pause (@var{n})\n\
 Suspend the execution of the program for @var{n} seconds.\n\
 \n\
-@var{n} is a positive real value and may be a fraction of a second.\n\
-\n\
 If invoked without an input arguments then the program is suspended until a\n\
 character is typed.\n\
 \n\
+@var{n} is a positive real value and may be a fraction of a second,\n\
+for example:\n\
+\n\
+@example\n\
+@group\n\
+tic; pause (0.05); toc\n\
+     @print{} Elapsed time is 0.05039 seconds.\n\
+@end group\n\
+@end example\n\
+\n\
 The following example prints a message and then waits 5 seconds before\n\
 clearing the screen.\n\
 \n\
 @example\n\
 @group\n\
-fprintf (stderr, \"wait please...\\n\");\n\
+disp (\"wait please...\");\n\
 pause (5);\n\
 clc;\n\
 @end group\n\
 @end example\n\
-@seealso{kbhit, sleep}\n\
+\n\
+@seealso{kbhit}\n\
 @end deftypefn")
 {
   octave_value_list retval;
@@ -803,81 +812,6 @@
 %!error (pause (1, 2))
 */
 
-DEFUN (sleep, args, ,
-       "-*- texinfo -*-\n\
-@deftypefn {} {} sleep (@var{seconds})\n\
-Suspend the execution of the program for the given number of seconds.\n\
-@seealso{usleep, pause}\n\
-@end deftypefn")
-{
-  octave_value_list retval;
-
-  if (args.length () != 1)
-    print_usage ();
-
-  double dval = args(0).double_value ();
-
-  if (xisnan (dval))
-    warning ("sleep: NaN is an invalid delay");
-  else
-    {
-      Fdrawnow ();
-      octave_sleep (dval);
-    }
-
-  return retval;
-}
-
-/*
-%!test
-%! sleep (1);
-
-%!error (sleep ())
-%!error (sleep (1, 2))
-*/
-
-DEFUN (usleep, args, ,
-       "-*- texinfo -*-\n\
-@deftypefn {} {} usleep (@var{microseconds})\n\
-Suspend the execution of the program for the given number of\n\
-microseconds.\n\
-\n\
-On systems where it is not possible to sleep for periods of time less than\n\
-one second, @code{usleep} will pause the execution for @code{round\n\
-(@var{microseconds} / 1e6)} seconds.\n\
-@seealso{sleep, pause}\n\
-@end deftypefn")
-{
-  octave_value_list retval;
-
-  if (args.length () != 1)
-    print_usage ();
-
-  double dval = args(0).double_value ();
-
-  if (xisnan (dval))
-    warning ("usleep: NaN is an invalid delay");
-  else
-    {
-      Fdrawnow ();
-
-      int delay = NINT (dval);
-
-      if (delay > 0)
-        octave_usleep (delay);
-    }
-
-  return retval;
-}
-
-/*
-%!test
-%! usleep (1000);
-
-%!error (usleep ())
-%!error (usleep (1, 2))
-*/
-
 // FIXME: maybe this should only return 1 if IEEE floating
 // point functions really work.
 

--- a/libinterp/corefcn/toplev.cc	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/toplev.cc	Thu Dec 17 16:04:13 2015 +0100
@@ -800,7 +800,7 @@
           // exiting for us.  Assume that job won't take more than a
           // day...
 
-          gnulib::sleep (86400);
+          octave_sleep (86400); // FIXME: really needed?
         }
     }
   else

--- a/libinterp/corefcn/utils.cc	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/utils.cc	Thu Dec 17 16:04:13 2015 +0100
@@ -1355,25 +1355,22 @@
 void
 octave_sleep (double seconds)
 {
-  if (seconds > 0)
-    {
-      double t;
+  if (seconds <= 0)
+    return;
 
-      unsigned int usec
-        = static_cast<unsigned int> (modf (seconds, &t) * 1000000);
+  double fraction = std::modf (seconds, &seconds);
+  fraction = std::floor (fraction * 1000000000); // nanoseconds
 
-      unsigned int sec
-        = ((t > std::numeric_limits<unsigned int>::max ())
-           ? std::numeric_limits<unsigned int>::max ()
-           : static_cast<unsigned int> (t));
+  time_t sec = ((seconds > std::numeric_limits<time_t>::max ())
+                ? std::numeric_limits<time_t>::max ()
+                : static_cast<time_t> (seconds));
 
-      // Versions of these functions that accept unsigned int args are
-      // defined in cutils.c.
-      octave_sleep (sec);
-      octave_usleep (usec);
+  // call GNULIB POSIX function
+  struct timespec delay = { sec, static_cast<long> (fraction) };
+  struct timespec remaining;
+  gnulib::nanosleep (&delay, &remaining);
 
-      octave_quit ();
-    }
+  octave_quit ();
 }
 
 DEFUN (isindex, args, ,

--- a/libinterp/corefcn/utils.h	Wed Dec 16 16:47:18 2015 -0800
+++ b/libinterp/corefcn/utils.h	Thu Dec 17 16:04:13 2015 +0100
@@ -32,8 +32,6 @@
 #include "dMatrix.h"
 #include "lo-utils.h"
 
-#include "cutils.h"
-
 class octave_value;
 class octave_value_list;
 class string_vector;

--- a/scripts/audio/@audioplayer/audioplayer.m	Wed Dec 16 16:47:18 2015 -0800
+++ b/scripts/audio/@audioplayer/audioplayer.m	Thu Dec 17 16:04:13 2015 +0100
@@ -114,11 +114,11 @@
 %! audio = randn (2, 2*fs) - 0.5;
 %! player = audioplayer (audio, fs);
 %! play (player);
-%! sleep (1);
+%! pause (1);
 %! pause (player);
-%! sleep (1);
+%! pause (1);
 %! resume (player);
-%! sleep (1);
+%! pause (1);
 %! stop (player);
 
 ## Tests of audioplayer must not actually play anything.
@@ -176,13 +176,13 @@
 #%!testif HAVE_PORTAUDIO
 #%! player = audioplayer (@callback, 44100);
 #%! play (player);
-#%! sleep (2);
+#%! pause (2);
 #%! stop (player);
 #%! assert (1);
 
 #%!testif HAVE_PORTAUDIO
 #%! player = audioplayer ("callback", 44100, 16);
 #%! play (player);
-#%! sleep (2);
+#%! pause (2);
 #%! stop (player);
 #%! assert (1);

--- a/scripts/audio/@audiorecorder/audiorecorder.m	Wed Dec 16 16:47:18 2015 -0800
+++ b/scripts/audio/@audiorecorder/audiorecorder.m	Thu Dec 17 16:04:13 2015 +0100
@@ -57,13 +57,13 @@
 %!demo
 %! recorder = audiorecorder (44100, 16, 2);
 %! record (recorder, 1);
-%! sleep (2);
+%! pause (2);
 %! player1 = audioplayer (recorder);
 %! player2 = getplayer (recorder);
 %! play (player1);
-%! sleep (2);
+%! pause (2);
 %! play (player2);
-%! sleep (2);
+%! pause (2);
 %! stop (player1);
 %! stop (player2);
 
@@ -119,7 +119,7 @@
 #%! recorder = audiorecorder (@callback_record, 44100);
 #%! unlink ("record.txt")
 #%! record (recorder);
-#%! sleep (2);
+#%! pause (2);
 #%! stop (recorder);
 #%! s = stat ("record.txt");
 #%! assert (s.size > 0);
@@ -128,7 +128,7 @@
 #%! recorder = audiorecorder (@callback_record, 44100);
 #%! unlink ("record.txt")
 #%! record (recorder);
-#%! sleep (2);
+#%! pause (2);
 #%! stop (recorder);
 #%! s = stat ("record.txt");
 #%! assert (s.size > 0);

--- a/scripts/deprecated/module.mk	Wed Dec 16 16:47:18 2015 -0800
+++ b/scripts/deprecated/module.mk	Thu Dec 17 16:04:13 2015 +0100
@@ -21,8 +21,10 @@
   scripts/deprecated/playaudio.m \
   scripts/deprecated/saveaudio.m \
   scripts/deprecated/setaudio.m \
+  scripts/deprecated/sleep.m \
   scripts/deprecated/syl.m \
   scripts/deprecated/usage.m \
+  scripts/deprecated/usleep.m \
   scripts/deprecated/wavread.m \
   scripts/deprecated/wavwrite.m
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/deprecated/sleep.m	Thu Dec 17 16:04:13 2015 +0100
@@ -0,0 +1,51 @@
+## Copyright (C) 1993-2015 John W. Eaton
+##
+## 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
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {} {} sleep (@var{seconds})\n\
+##
+## @code{sleep} is deprecated and will be removed in Octave version 4.6.
+## Use @code{pause} instead.
+##
+## Suspend the execution of the program for the given number of seconds.
+##
+## @seealso{pause}
+## @end deftypefn
+
+function [] = sleep (seconds)
+
+  persistent warned = false;
+  if (! warned)
+    warned = true;
+    warning ("Octave:deprecated-function",
+             "sleep is obsolete and will be removed from a future version of Octave, please use pause instead");
+  endif
+
+  if (nargin == 1)
+    pause (seconds);
+  else
+    print_usage ();
+  endif
+
+endfunction
+
+%!test
+%! sleep (1);
+
+%!error (sleep ())
+%!error (sleep (1, 2))

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/deprecated/usleep.m	Thu Dec 17 16:04:13 2015 +0100
@@ -0,0 +1,52 @@
+## Copyright (C) 1993-2015 John W. Eaton
+##
+## 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
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {} {} usleep (@var{microseconds})\n\
+##
+## @code{usleep} is deprecated and will be removed in Octave version 4.6.
+## Use @code{pause} instead.
+##
+## Suspend the execution of the program for the given number of
+## microseconds (1e-6 seconds).
+##
+## @seealso{pause}
+## @end deftypefn
+
+function [] = usleep (microseconds)
+
+  persistent warned = false;
+  if (! warned)
+    warned = true;
+    warning ("Octave:deprecated-function",
+             "usleep is obsolete and will be removed from a future version of Octave, please use pause instead");
+  endif
+
+  if (nargin == 1)
+    pause (microseconds / 1e6);
+  else
+    print_usage ();
+  endif
+
+endfunction
+
+%!test
+%! usleep (1000);
+
+%!error (usleep ())
+%!error (usleep (1, 2))

--- a/scripts/plot/util/ginput.m	Wed Dec 16 16:47:18 2015 -0800
+++ b/scripts/plot/util/ginput.m	Thu Dec 17 16:04:13 2015 +0100
@@ -85,7 +85,7 @@
       endif
 
       ## Release CPU.
-      sleep (0.01);
+      pause (0.01);
 
       [x, y, n0, button] = ginput_accumulator (-1, 0, 0, 0);
     until ((n > -1 && n0 >= n) || n0 < 0)

--- a/scripts/plot/util/private/__gnuplot_get_var__.m	Wed Dec 16 16:47:18 2015 -0800
+++ b/scripts/plot/util/private/__gnuplot_get_var__.m	Thu Dec 17 16:04:13 2015 +0100
@@ -117,7 +117,7 @@
       while (isempty (str))
         str = fread (istream, "*char")';
         if (isempty (str))
-          sleep (0.05);
+          pause (0.05);
         else
           str = regexp (str, 'OCTAVE:.*', "match");
           str = str{end}(8:end);

--- a/scripts/plot/util/private/__gnuplot_ginput__.m	Wed Dec 16 16:47:18 2015 -0800
+++ b/scripts/plot/util/private/__gnuplot_ginput__.m	Thu Dec 17 16:04:13 2015 +0100
@@ -110,7 +110,7 @@
         while (isempty (str))
           str = fread (istream, "*char")';
           if (isempty (str))
-            sleep (0.05);
+            pause (0.05);
           else
             str = regexp (str, 'OCTAVE:\s+[-+.\d]+\s+[-+.\d]+\s+\d*', 'match');
           endif