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########################################################################
##
## Copyright (C) 1998-2024 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{tf} =} isletter (@var{s})
## Return a logical array which is true where the elements of @var{s}
## are letters and false where they are not.
##
## This is an alias for the @code{isalpha} function.
## @seealso{isalpha, isdigit, ispunct, isspace, iscntrl, isalnum}
## @end deftypefn
function tf = isletter (s)
if (nargin < 1)
print_usage ();
endif
tf = isalpha (s);
endfunction
%!error <Invalid call> isletter ()
%!error isletter ("a", "b")
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