Mercurial > octave
view scripts/miscellaneous/list_primes.m @ 31197:8d4c87e88d0e
maint: Merge stable to default.
author | Markus Mützel <markus.muetzel@gmx.de> |
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date | Tue, 23 Aug 2022 19:45:19 +0200 |
parents | 5d3faba0342e |
children | 597f3ee61a48 |
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######################################################################## ## ## Copyright (C) 1993-2022 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 {} {@var{p} =} list_primes () ## @deftypefnx {} {@var{p} =} list_primes (@var{n}) ## List the first @var{n} primes. ## ## If @var{n} is unspecified, the first 25 primes are listed. ## @seealso{primes, isprime} ## @end deftypefn function p = list_primes (n = 25) if (! isreal (n) || ! isscalar (n)) error ("list_primes: N must be a real scalar"); endif n = floor (n); if (n < 1) p = []; return; elseif (n == 1) p = 2; return; endif list = primes (n * log (5 * n)); if (numel (list) < n) ## Algorithm tested up to n=10,000 without failure. error ("list_primes: Algorithm failed. Try primes (n*log (6*n))(1:n)"); endif p = list(1:n); endfunction %!assert (list_primes (), [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, ... %! 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]) %!assert (list_primes (5), [2, 3, 5, 7, 11]) %!assert (list_primes (0), []) %!assert (list_primes (1), [2]) ## Test input validation %!error <N must be a real scalar> list_primes (i) %!error <N must be a real scalar> list_primes ([1 2])