## Copyright (C) 1995, 1996, 1997 Kurt Hornik ## ## This program 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 2, or (at your option) ## any later version. ## ## This program 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 this file. If not, write to the Free Software Foundation, ## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. ## usage: weibull_rnd (alpha, sigma [, r, c]) ## ## weibull_rnd (alpha, sigma) returns a matrix of random samples from ## the Weibull distribution with parameters alpha and sigma. The size of ## the matrix is the common size of alpha and sigma. ## ## weibull_rnd (alpha, sigma, r, c) returns an r by c matrix of random ## samples from the Weibull distribution with parameters alpha and sigma ## which must be scalar or of size r by c. ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> ## Description: Random deviates from the Weibull distribution function rnd = weibull_rnd (shape, scale, r, c) if (nargin == 4) if ( !(is_scalar (r) && (r > 0) && (r == round (r))) ) error ("weibull_rnd: r must be a positive integer"); endif if ( !(is_scalar (c) && (c > 0) && (c == round (c))) ) error ("weibull_rnd: c must be a positive integer"); endif [retval, shape, scale] = common_size (shape, scale, zeros (r, c)); if (retval > 0) error (strcat("weibull_rnd: ", "alpha and sigma must be scalar or of size ", sprintf ("%d by %d", r, c))); endif elseif (nargin == 2) [retval, shape, scale] = common_size (shape, scale); if (retval > 0) error (strcat("weibull_rnd: ", "alpha and sigma must be of common size or scalar")); endif else usage ("weibull_rnd (alpha, sigma [, r, c])"); endif [r, c] = size (shape); s = r * c; shape = reshape (shape, 1, s); scale = reshape (scale, 1, s); rnd = NaN * ones (1, s); k = find ((shape > 0) & (shape < Inf) & (scale > 0) & (scale < Inf)); if any (k) rnd(k) = (scale(k) .* (- log (1 - rand (1, length (k)))) .^ (1 ./ shape(k))); endif rnd = reshape (rnd, r, c); endfunction

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