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########################################################################
##
## Copyright (C) 1993-2026 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 {} {} semilogy (@var{y})
## @deftypefnx {} {} semilogy (@var{x}, @var{y})
## @deftypefnx {} {} semilogy (@var{x}, @var{y}, @var{property}, @var{value}, @dots{})
## @deftypefnx {} {} semilogy (@var{x}, @var{y}, @var{fmt})
## @deftypefnx {} {} semilogy (@var{h}, @dots{})
## @deftypefnx {} {@var{h} =} semilogy (@dots{})
## Produce a 2-D plot using a logarithmic scale for the y-axis.
##
## See the documentation of @code{plot} for a description of the
## arguments that @code{semilogy} will accept.
##
## If the first argument @var{hax} is an axes handle, then plot into this axes,
## rather than the current axes returned by @code{gca}.
##
## The optional return value @var{h} is a graphics handle to the created plot.
## @seealso{plot, semilogx, loglog}
## @end deftypefn
function h = semilogy (varargin)
[hax, varargin, nargs] = __plt_get_axis_arg__ ("semilogy", varargin{:});
if (nargs < 1)
print_usage ();
endif
hax = newplot (hax);
set (hax, "yscale", "log");
if (! ishold (hax))
set (hax, "yminortick", "on", "box", "on");
endif
htmp = __plt__ ("semilogy", hax, varargin{:});
if (nargout > 0)
h = htmp;
endif
endfunction
%!demo
%! clf;
%! x = 1:0.01:10;
%! y = (x .* (1 + rand (size (x)))) .^ 2;
%! semilogy (x, y);
%! title ({"semilogx() plot", "Y-axis is logarithmic"});
%!demo
%! clf;
%! x = logspace (-5, 1, 10);
%! y = logspace (-5, 1, 10);
%!
%! subplot (2,1,1);
%! semilogy (x, y);
%! title ("semilogy (x, y)");
%!
%! subplot (2,1,2);
%! semilogy (x, -y);
%! title ("semilogy (x, -y)");
%!demo
%! clf;
%! x = logspace (-5, 1, 10);
%! y = logspace (-5, 1, 10);
%!
%! subplot (2,1,1);
%! semilogy (x, y);
%! set (gca, "ydir", "reverse", "positionconstraint", "outerposition");
%! title ({"semilogy (x, y)", "ydir = reversed"});
%!
%! subplot (2,1,2);
%! semilogy (x, -y);
%! set (gca, "ydir", "reverse", "positionconstraint", "outerposition");
%! title ({"semilogy (x, -y)", "ydir = reversed"});
%!test
%! hf = figure ("visible", "off");
%! unwind_protect
%! a = logspace (-5, 1, 10);
%! b = logspace (-5, 1, 10);
%! semilogy (a, b);
%! assert (get (gca, "yscale"), "log");
%! assert (get (gca, "xscale"), "linear");
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
%!test
%! hf = figure ("visible", "off");
%! unwind_protect
%! a = logspace (-5, 1, 10);
%! b =-logspace (-5, 1, 10);
%! semilogy (a, b);
%! axis tight;
%! assert (all (get (gca, "ytick") < 0));
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
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