########################################################################
##
## Copyright (C) 2019-2020 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.
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
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## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, see
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########################################################################

## -*- texinfo -*-
## @deftypefn {} {} mustBeNonzero (@var{x})
##
## Requires that input @var{x} is not zero.
##
## Raises an error if any element of the input @var{x} is zero, as determined
## by @code{@var{x} != 0}.
##
## @end deftypefn

# TODO: Should NaN be considered nonzero? It fits the formal definition above,
# but that may not be the spirit of the test. And it's not equal to any non-zero
# value.

function mustBeNonzero (x)
  tf = x != 0;
  tf = tf(:);
  if ! all (tf)
    label = inputname (1);
    if isempty (label)
      label = "input";
    endif
    ix_bad = find (! tf);
    errmsg = sprintf ( ...
      "%s must be non-zero; got %d elements that were zero: indexes %s", ...
      label, numel (ix_bad), mat2str (ix_bad));
    error (errmsg);
  endif
endfunction

%!test
%! mustBeNonzero (1)
%! mustBeNonzero (-1)
%! mustBeNonzero ([-5:-1 1:5])
%! mustBeNonzero (Inf)
%! mustBeNonzero (-Inf)
%! mustBeNonzero (NaN)
%! mustBeNonzero (eps)

%!error mustBeNonzero ()
%!error mustBeNonzero (0)
%!error mustBeNonzero (-10:10)