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view scripts/statistics/std.m @ 27898:4d6d21839dfd
remove Author: jwe and Adapted-by: jwe lines from source files
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Files affected: url-transfer.cc, url-transfer.h, acot.m, acoth.m,
acsc.m, acsch.m, asec.m, asech.m, cot.m, coth.m, csc.m, csch.m, sec.m,
sech.m, cart2pol.m, cart2sph.m, deal.m, fliplr.m, flipud.m, int2str.m,
logspace.m, num2str.m, pol2cart.m, rot90.m, sortrows.m, sph2cart.m,
waitbar.m, doc.m, hsv2rgb.m, rgb2hsv.m, beep.m, isstr.m, setstr.m,
strmatch.m, cond.m, rank.m, trace.m, bug_report.m, cast.m, delete.m,
dir.m, list_primes.m, ls.m, ls_command.m, menu.m, pack.m, recycle.m,
substruct.m, version.m, glpk.m, axis.m, box.m, grid.m,
__axis_label__.m, text.m, title.m, view.m, xlabel.m, ylabel.m,
zlabel.m, bar.m, barh.m, comet3.m, hist.m, line.m, loglog.m, mesh.m,
patch.m, plot.m, polar.m, __bar__.m, __line__.m, __plt__.m,
__stem__.m, semilogx.m, semilogy.m, sombrero.m, stairs.m, stem.m,
surface.m, __default_plot_options__.m, __gnuplot_drawnow__.m,
__next_line_color__.m, __plt_get_axis_arg__.m, __pltopt__.m, clf.m,
closereq.m, gca.m, gnuplot_binary.in.m, isfigure.m, meshgrid.m,
__gnuplot_draw_axes__.m, __gnuplot_draw_figure__.m, shg.m, addpref.m,
getpref.m, ispref.m, loadprefs.m, prefsfile.m, saveprefs.m, rmpref.m,
setpref.m, ismember.m, setdiff.m, union.m, hankel.m, hilb.m, vander.m,
median.m, std.m, cstrcat.m, isletter.m, str2num.m, strcat.m,
oruntests.m, rundemos.m, asctime.m, clock.m, ctime.m, date.m, etime.m,
is_leap_year.m.
author | John W. Eaton <jwe@octave.org> |
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date | Thu, 02 Jan 2020 15:43:01 -0500 |
parents | 00f796120a6d |
children | b442ec6dda5c |
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## Copyright (C) 1996-2019 John W. Eaton ## ## 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 {} {} std (@var{x}) ## @deftypefnx {} {} std (@var{x}, @var{opt}) ## @deftypefnx {} {} std (@var{x}, @var{opt}, @var{dim}) ## Compute the standard deviation of the elements of the vector @var{x}. ## ## The standard deviation is defined as ## @tex ## $$ ## {\rm std} (x) = \sigma = \sqrt{{\sum_{i=1}^N (x_i - \bar{x})^2 \over N - 1}} ## $$ ## where $\bar{x}$ is the mean value of @var{x} and $N$ is the number of elements of @var{x}. ## @end tex ## @ifnottex ## ## @example ## @group ## std (@var{x}) = sqrt ( 1/(N-1) SUM_i (@var{x}(i) - mean(@var{x}))^2 ) ## @end group ## @end example ## ## @noindent ## where @math{N} is the number of elements of the @var{x} vector. ## @end ifnottex ## ## If @var{x} is a matrix, compute the standard deviation for each column and ## return them in a row vector. ## ## The argument @var{opt} determines the type of normalization to use. ## Valid values are ## ## @table @asis ## @item 0: ## normalize with @math{N-1}, provides the square root of the best unbiased ## estimator of the variance [default] ## ## @item 1: ## normalize with @math{N}, this provides the square root of the second ## moment around the mean ## @end table ## ## If the optional argument @var{dim} is given, operate along this dimension. ## @seealso{var, bounds, mad, range, iqr, mean, median} ## @end deftypefn function retval = std (x, opt = 0, dim) if (nargin < 1 || nargin > 3) print_usage (); endif if (! (isnumeric (x) || islogical (x))) error ("std: X must be a numeric vector or matrix"); endif if (isempty (opt)) opt = 0; elseif (! isscalar (opt) || (opt != 0 && opt != 1)) error ("std: normalization OPT must be 0 or 1"); endif nd = ndims (x); sz = size (x); if (nargin < 3) ## Find the first non-singleton dimension. (dim = find (sz > 1, 1)) || (dim = 1); else if (! (isscalar (dim) && dim == fix (dim) && dim > 0)) error ("std: DIM must be an integer and a valid dimension"); endif endif n = size (x, dim); if (n == 1 || isempty (x)) if (isa (x, "single")) retval = zeros (sz, "single"); else retval = zeros (sz); endif else retval = sqrt (sumsq (center (x, dim), dim) / (n - 1 + opt)); endif endfunction %!test %! x = ones (10, 2); %! y = [1, 3]; %! assert (std (x), [0, 0]); %! assert (std (y), sqrt (2), sqrt (eps)); %! assert (std (x, 0, 2), zeros (10, 1)); %!assert (std (ones (3, 1, 2), 0, 2), zeros (3, 1, 2)) %!assert (std ([1 2], 0), sqrt (2)/2, 5*eps) %!assert (std ([1 2], 1), 0.5, 5*eps) %!assert (std (1), 0) %!assert (std (single (1)), single (0)) %!assert (std ([]), []) %!assert (std (ones (1,3,0,2)), ones (1,3,0,2)) %!assert (std ([1 2 3], [], 3), [0 0 0]) ## Test input validation %!error std () %!error std (1, 2, 3, 4) %!error <X must be a numeric> std (['A'; 'B']) %!error <OPT must be 0 or 1> std (1, 2) %!error <DIM must be an integer> std (1, [], ones (2,2)) %!error <DIM must be an integer> std (1, [], 1.5) %!error <DIM must be .* a valid dimension> std (1, [], 0)