Eliminate unneeded verification of nargin, nargout in m-files. * FIRfilter.m, FIRfilter_aggregation.m, get.m, polynomial.m, polynomial_superiorto.m, polynomial2.m, makeUniqueStrings.m, base64decode.m, base64encode.m, cd.m, lin2mu.m, record.m, sound.m, soundsc.m, accumarray.m, accumdim.m, bitcmp.m, bitset.m, cart2pol.m, celldisp.m, circshift.m, cplxpair.m, cumtrapz.m, flip.m, idivide.m, interpft.m, logspace.m, pol2cart.m, polyarea.m, postpad.m, prepad.m, rat.m, rot90.m, rotdim.m, shift.m, shiftdim.m, sortrows.m, trapz.m, dsearch.m, dsearchn.m, getappdata.m, getpixelposition.m, guidata.m, guihandles.m, isappdata.m, listfonts.m, uigetdir.m, waitforbuttonpress.m, __makeinfo__.m, doc.m, get_first_help_sentence.m, autumn.m, bone.m, brighten.m, cmpermute.m, cmunique.m, colorcube.m, contrast.m, cool.m, copper.m, cubehelix.m, flag.m, gray.m, gray2ind.m, hot.m, hsv.m, im2double.m, im2frame.m, imformats.m, jet.m, lines.m, ocean.m, pink.m, prism.m, rainbow.m, rgbplot.m, spinmap.m, spring.m, summer.m, viridis.m, white.m, winter.m, beep.m, importdata.m, is_valid_file_id.m, javachk.m, javaclasspath.m, findstr.m, genvarname.m, strmatch.m, bandwidth.m, commutation_matrix.m, cond.m, cross.m, isdefinite.m, ishermitian.m, issymmetric.m, krylov.m, linsolve.m, logm.m, lscov.m, null.m, ordeig.m, orth.m, rank.m, rref.m, vecnorm.m, bunzip2.m, citation.m, computer.m, copyfile.m, dir.m, dos.m, fileattrib.m, gunzip.m, inputParser.m, inputname.m, ismac.m, ispc.m, isunix.m, license.m, list_primes.m, methods.m, mkdir.m, movefile.m, nargchk.m, news.m, orderfields.m, recycle.m, tar.m, unix.m, unpack.m, untar.m, unzip.m, ver.m, version.m, what.m, zip.m, decic.m, fminbnd.m, fminunc.m, fsolve.m, fzero.m, glpk.m, humps.m, lsqnonneg.m, optimget.m, pqpnonneg.m, sqp.m, pathdef.m, camlookat.m, hidden.m, specular.m, plotmatrix.m, smooth3.m, sombrero.m, stemleaf.m, __gnuplot_drawnow__.m, __opengl_info__.m, ancestor.m, cla.m, close.m, closereq.m, copyobj.m, gca.m, gcf.m, ginput.m, graphics_toolkit.m, groot.m, hgload.m, hgsave.m, isgraphics.m, ishold.m, linkaxes.m, meshgrid.m, newplot.m, refresh.m, refreshdata.m, rotate.m, saveas.m, struct2hdl.m, conv.m, mkpp.m, mpoles.m, padecoef.m, pchip.m, polyder.m, polyfit.m, polygcd.m, polyint.m, polyout.m, polyval.m, ppder.m, ppint.m, getpref.m, ispref.m, rmpref.m, profexport.m, profshow.m, powerset.m, arch_fit.m, arma_rnd.m, blackman.m, detrend.m, diffpara.m, fftconv.m, fftfilt.m, filter2.m, freqz.m, freqz_plot.m, hamming.m, hanning.m, sinetone.m, sinewave.m, spectral_adf.m, spectral_xdf.m, stft.m, unwrap.m, gplot.m, ichol.m, ilu.m, spdiags.m, sprand.m, sprandn.m, spstats.m, svds.m, treelayout.m, treeplot.m, betainc.m, betaincinv.m, ellipke.m, gammainc.m, gammaincinv.m, legendre.m, pow2.m, hankel.m, pascal.m, rosser.m, toeplitz.m, bounds.m, corr.m, cov.m, histc.m, kendall.m, kurtosis.m, mad.m, mode.m, moment.m, prctile.m, quantile.m, range.m, ranks.m, run_count.m, skewness.m, spearman.m, std.m, var.m, zscore.m, dec2base.m, dec2bin.m, dec2hex.m, index.m, mat2str.m, native2unicode.m, ostrsplit.m, strjoin.m, strjust.m, strtok.m, substr.m, unicode2native.m, untabify.m, __debug_octave__.m, demo.m, example.m, fail.m, oruntests.m, dump_demos.m, speed.m, test.m, date.m, datenum.m, datestr.m, datevec.m, is_leap_year.m, now.m, weekday.m: Eliminate unneeded verification of nargin, nargout in m-files now that the interpreter checks these values.

########################################################################
##
## Copyright (C) 1995-2020 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.
##
## 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 {} {} detrend (@var{x}, @var{p})
## If @var{x} is a vector, @code{detrend (@var{x}, @var{p})} removes the
## best fit of a polynomial of order @var{p} from the data @var{x}.
##
## If @var{x} is a matrix, @code{detrend (@var{x}, @var{p})} does the same
## for each column in @var{x}.
##
## The second argument @var{p} is optional.  If it is not specified, a value of
## 1 is assumed.  This corresponds to removing a linear trend.
##
## The order of the polynomial can also be given as a string, in which case
## @var{p} must be either @qcode{"constant"} (corresponds to @code{@var{p}=0})
## or @qcode{"linear"} (corresponds to @code{@var{p}=1}).
## @seealso{polyfit}
## @end deftypefn

function y = detrend (x, p = 1)

  if (nargin < 1)
    print_usage ();
  endif

  if (! isnumeric (x) || ndims (x) > 2)
    error ("detrend: X must be a numeric vector or matrix");
  endif

  if (ischar (p) && strcmpi (p, "constant"))
    p = 0;
  elseif (ischar (p) && strcmpi (p, "linear"))
    p = 1;
  elseif (! isscalar (p) || p < 0 || p != fix (p))
    error ("detrend: P must be \"constant\", \"linear\", or a positive integer");
  endif

  [m, n] = size (x);
  if (m == 1)
    x = x.';
  endif

  r = rows (x);
  b = ((1 : r).' * ones (1, p + 1)) .^ (ones (r, 1) * (0 : p));
  y = x - b * (b \ x);

  if (m == 1)
    y = y.';
  endif

endfunction


%!test
%! N = 32;
%! x = (0:1:N-1)/N + 2;
%! y = detrend (x);
%! assert (abs (y(:)) < 20*eps);

%!test
%! N = 32;
%! t = (0:1:N-1)/N;
%! x = t .* t + 2;
%! y = detrend (x,2);
%! assert (abs (y(:)) < 30*eps);

%!test
%! N = 32;
%! t = (0:1:N-1)/N;
%! x = [t;4*t-3].';
%! y = detrend (x);
%! assert (abs (y(:)) < 20*eps);

%!test
%! N = 32;
%! x = ((0:1:N-1)/N + 2) * 1i;
%! y = detrend (x);
%! assert (abs (y(:)) < 20*eps);

## Test input validation
%!error detrend ()
%!error detrend (1, 2, 3)
%!error detrend ("a")
%!error detrend (true)
%!error detrend (1, "invalid")
%!error detrend (1, -1)
%!error detrend (1, 1.25)