--- a/doc/interpreter/octave.texi	Fri Jan 28 06:47:58 2000 +0000
+++ b/doc/interpreter/octave.texi	Fri Jan 28 09:14:34 2000 +0000
@@ -161,6 +161,7 @@
 
 
 
+
 @detailmenu
  --- The Detailed Node Listing ---
 
@@ -284,6 +285,7 @@
 * The if Statement::            
 * The switch Statement::        
 * The while Statement::         
+* The do-until Statement::      
 * The for Statement::           
 * The break Statement::         
 * The continue Statement::      
@@ -391,6 +393,7 @@
 Statistics
 
 * Basic Statistical Functions::  
+* Tests::                       
 * Models::                      
 * Distributions::               
 

--- a/doc/interpreter/stmt.txi	Fri Jan 28 06:47:58 2000 +0000
+++ b/doc/interpreter/stmt.txi	Fri Jan 28 09:14:34 2000 +0000
@@ -35,6 +35,7 @@
 * The if Statement::            
 * The switch Statement::        
 * The while Statement::         
+* The do-until Statement::      
 * The for Statement::           
 * The break Statement::         
 * The continue Statement::      
@@ -293,7 +294,7 @@
 
 @DOCSTRING(warn_variable_switch_label)
 
-@node The while Statement, The for Statement, The switch Statement, Statements
+@node The while Statement, The do-until Statement, The switch Statement, Statements
 @section The @code{while} Statement
 @cindex @code{while} statement
 @cindex @code{endwhile} statement
@@ -365,7 +366,57 @@
 @xref{The if Statement}, for a description of the variable
 @code{warn_assign_as_truth_value}.
 
-@node The for Statement, The break Statement, The while Statement, Statements
+@node The do-until Statement, The for Statement, The while Statement, Statements
+@section The @code{do-until} Statement
+@cindex @code{do-until} statement
+
+The @code{do-until} statement is similar to the @code{while} statement,
+except that it repeatedly executes a statement until a condition becomes
+true, and the test of the condition is at the end of the loop, so the
+body of the loop is always executed at least once.  As with the
+condition in an @code{if} statement, the condition in a @code{do-until}
+statement is considered true if its value is non-zero, and false if its
+value is zero.  If the value of the conditional expression in a
+@code{do-until} statement is a vector or a matrix, it is considered 
+true only if @emph{all} of the elements are non-zero.
+
+Octave's @code{do-until} statement looks like this:
+
+@example
+@group
+do
+  @var{body}
+until (@var{condition})
+@end group
+@end example
+
+@noindent
+Here @var{body} is a statement or list of statements that we call the
+@dfn{body} of the loop, and @var{condition} is an expression that
+controls how long the loop keeps running.
+
+This example creates a variable @code{fib} that contains the first ten
+elements of the Fibonacci sequence.
+
+@example
+@group
+fib = ones (1, 10);
+i = 2;
+do
+  i++;
+  fib (i) = fib (i-1) + fib (i-2);
+until (i == 10)
+@end group
+@end example
+
+A newline is not required between the @code{do} keyword and the
+body; but using one makes the program clearer unless the body is very
+simple.
+
+@xref{The if Statement}, for a description of the variable
+@code{warn_assign_as_truth_value}.
+
+@node The for Statement, The break Statement, The do-until Statement, Statements
 @section The @code{for} Statement
 @cindex @code{for} statement
 @cindex @code{endfor} statement

--- a/src/ChangeLog	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/ChangeLog	Fri Jan 28 09:14:34 2000 +0000
@@ -1,3 +1,15 @@
+2000-01-28  John W. Eaton  <jwe@bevo.che.wisc.edu>
+
+	* parse.y (evaluating_function_body): New global flag.
+	* ov-usr-fcn.cc (octave_user_function::do_index_op):
+	Protect and set it here.
+	* parse.y (make_break_command, make_return_command): Check it here.
+
+	* error.cc (warning_state): New global flag.
+	(warning): Set it here.
+	* lex.l (reset_parser): Clear it here.
+	* parse.y (fold): Check it here.
+
 2000-01-27  John W. Eaton  <jwe@bevo.che.wisc.edu>
 
 	* pt-walk.h (tree_walker::visit_do_until_command): New pure virtual.

--- a/src/error.cc	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/error.cc	Fri Jan 28 09:14:34 2000 +0000
@@ -46,6 +46,9 @@
 // Current error state.
 int error_state = 0;
 
+// Current warning state.
+int warning_state = 0;
+
 // Tell the error handler whether to print messages, or just store
 // them for later.  Used for handling errors in eval() and
 // the `unwind_protect' statement.
@@ -171,6 +174,7 @@
 {
   va_list args;
   va_start (args, fmt);
+  warning_state = 1;
   verror ("warning", fmt, args);
   va_end (args);
 }

--- a/src/error.h	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/error.h	Fri Jan 28 09:14:34 2000 +0000
@@ -39,6 +39,9 @@
 // Current error state.
 extern int error_state;
 
+// Current warning state.
+extern int warning_state;
+
 // Tell the error handler whether to print messages, or just store
 // them for later.  Used for handling errors in eval() and
 // the `unwind_protect' statement.

--- a/src/lex.l	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/lex.l	Fri Jan 28 09:14:34 2000 +0000
@@ -739,6 +739,7 @@
   // Start off on the right foot.
   BEGIN 0;
   error_state = 0;
+  warning_state = 0;
 
   // We do want a prompt by default.
   promptflag = 1;

--- a/src/ov-usr-fcn.cc	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/ov-usr-fcn.cc	Fri Jan 28 09:14:34 2000 +0000
@@ -47,6 +47,7 @@
 #include "toplev.h"
 #include "unwind-prot.h"
 #include "utils.h"
+#include "parse.h"
 #include "variables.h"
 
 // If TRUE, variables returned from functions have default values even
@@ -378,6 +379,9 @@
 
     // Evaluate the commands that make up the function.
 
+    unwind_protect_bool (evaluating_function_body);
+    evaluating_function_body = true;
+
     octave_value_list tmp = cmd_list->eval ();
 
     octave_value last_computed_value;

--- a/src/parse.h	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/parse.h	Fri Jan 28 09:14:34 2000 +0000
@@ -69,6 +69,11 @@
 // the command line.
 extern bool input_from_command_line_file;
 
+// TRUE means that we are in the process of evaluating a function
+// body.  The parser might be called in that case if we are looking at
+// an eval() statement.
+extern bool evaluating_function_body;
+
 // TRUE means warn about function files that have time stamps in the future.
 extern bool Vwarn_future_time_stamp;
 

--- a/src/parse.y	Fri Jan 28 06:47:58 2000 +0000
+++ b/src/parse.y	Fri Jan 28 09:14:34 2000 +0000
@@ -117,6 +117,11 @@
 // the command line.
 bool input_from_command_line_file = true;
 
+// TRUE means that we are in the process of evaluating a function
+// body.  The parser might be called in that case if we are looking at
+// an eval() statement.
+bool evaluating_function_body = false;
+
 // Forward declarations for some functions defined at the bottom of
 // the file.
 
@@ -1617,7 +1622,7 @@
     {
       octave_value tmp = e->rvalue ();
 
-      if (! error_state)
+      if (! (error_state || warning_state))
 	{
 	  tree_constant *tc_retval = new tree_constant (tmp);
 
@@ -1666,7 +1671,7 @@
     {
       octave_value tmp = e->rvalue ();
 
-      if (! error_state)
+      if (! (error_state || warning_state))
 	{
 	  tree_constant *tc_retval = new tree_constant (tmp);
 
@@ -1724,7 +1729,7 @@
 	    {
 	      octave_value tmp = e->rvalue ();
 
-	      if (! error_state)
+	      if (! (error_state || warning_state))
 		{
 		  tree_constant *tc_retval = new tree_constant (tmp);
 
@@ -2143,7 +2148,8 @@
   int l = break_tok->line ();
   int c = break_tok->column ();
 
-  if (lexer_flags.looping || lexer_flags.defining_func || reading_script_file)
+  if (lexer_flags.looping || lexer_flags.defining_func
+      || reading_script_file || evaluating_function_body)
     retval = new tree_break_command (l, c);
   else
     retval = new tree_no_op_command ("break", l, c);
@@ -2179,7 +2185,8 @@
   int l = return_tok->line ();
   int c = return_tok->column ();
 
-  if (lexer_flags.defining_func || reading_script_file)
+  if (lexer_flags.defining_func || reading_script_file
+      || evaluating_function_body)
     retval = new tree_return_command (l, c);
   else
     retval = new tree_no_op_command ("return", l, c);
@@ -2554,7 +2561,7 @@
     {
       octave_value tmp = m->rvalue ();
 
-      if (! error_state)
+      if (! (error_state || warning_state))
 	{
 	  tree_constant *tc_retval = new tree_constant (tmp);