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doc: Update more docstrings to have one sentence summary as first line. Reviewed specfun, special-matrix, testfun, and time script directories. * scripts/specfun/expint.m, scripts/specfun/isprime.m, scripts/specfun/legendre.m, scripts/specfun/primes.m, scripts/specfun/reallog.m, scripts/specfun/realsqrt.m, scripts/special-matrix/gallery.m, scripts/special-matrix/hadamard.m, scripts/special-matrix/hankel.m, scripts/special-matrix/hilb.m, scripts/special-matrix/invhilb.m, scripts/special-matrix/magic.m, scripts/special-matrix/pascal.m, scripts/special-matrix/rosser.m, scripts/special-matrix/toeplitz.m, scripts/special-matrix/vander.m, scripts/special-matrix/wilkinson.m, scripts/testfun/assert.m, scripts/testfun/demo.m, scripts/testfun/example.m, scripts/testfun/fail.m, scripts/testfun/rundemos.m, scripts/testfun/runtests.m, scripts/testfun/speed.m, scripts/time/asctime.m, scripts/time/calendar.m, scripts/time/clock.m, scripts/time/ctime.m, scripts/time/datenum.m, scripts/time/datestr.m, scripts/time/datevec.m, scripts/time/etime.m, scripts/time/is_leap_year.m, scripts/time/now.m, scripts/time/weekday.m: Update more docstrings to have one sentence summary as first line.
author Rik <rik@octave.org>
date Sun, 03 May 2015 17:00:11 -0700
parents 9fc020886ae9
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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4197fc428c7d maint: Update copyright notices for 2015.
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1 ## Copyright (C) 1999-2015 Peter Ekberg
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} wilkinson (@var{n})
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21 ## Return the Wilkinson matrix of order @var{n}.
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22 ##
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23 ## Wilkinson matrices are symmetric and tridiagonal with pairs of nearly, but
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24 ## not exactly, equal eigenvalues. They are useful in testing the behavior and
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25 ## performance of eigenvalue solvers.
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26 ##
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27 ## @seealso{rosser, eig}
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28 ## @end deftypefn
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29
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30 ## Author: Peter Ekberg
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31 ## (peda)
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32
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33 function retval = wilkinson (n)
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34
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35 if (nargin != 1)
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36 print_usage ();
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37 endif
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38
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39 if (! (isscalar (n) && n >= 0 && (n == fix (n))))
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40 error ("wilkinson: N must be a non-negative integer");
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41 endif
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42
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43 side = ones (n-1, 1);
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44 center = abs (-(n-1)/2:(n-1)/2);
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45 retval = diag (side, -1) + diag (center) + diag (side, 1);
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46
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47 endfunction
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50 %!assert (wilkinson (0), [])
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51 %!assert (wilkinson (1), 0)
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52 %!assert (wilkinson (2), [0.5,1;1,0.5])
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53 %!assert (wilkinson (3), [1,1,0;1,0,1;0,1,1])
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54 %!assert (wilkinson (4), [1.5,1,0,0;1,0.5,1,0;0,1,0.5,1;0,0,1,1.5])
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55
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56 ## Test input validation
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57 %!error wilkinson ()
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58 %!error wilkinson (1,2)
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59 %!error <N must be a non-negative integer> wilkinson (ones (2))
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60 %!error <N must be a non-negative integer> wilkinson (-1)
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61 %!error <N must be a non-negative integer> wilkinson (1.5)
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