3191
|
1 ## Copyright (C) 1995, 1996, 1997 Kurt Hornik |
3426
|
2 ## |
3922
|
3 ## This file is part of Octave. |
|
4 ## |
|
5 ## Octave is free software; you can redistribute it and/or modify it |
|
6 ## under the terms of the GNU General Public License as published by |
3191
|
7 ## the Free Software Foundation; either version 2, or (at your option) |
|
8 ## any later version. |
3426
|
9 ## |
3922
|
10 ## Octave is distributed in the hope that it will be useful, but |
3191
|
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
|
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
3426
|
13 ## General Public License for more details. |
|
14 ## |
3191
|
15 ## You should have received a copy of the GNU General Public License |
3922
|
16 ## along with Octave; see the file COPYING. If not, write to the Free |
5307
|
17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
|
18 ## 02110-1301, USA. |
3191
|
19 |
3456
|
20 ## -*- texinfo -*- |
|
21 ## @deftypefn {Function File} {} exponential_cdf (@var{x}, @var{lambda}) |
|
22 ## For each element of @var{x}, compute the cumulative distribution |
|
23 ## function (CDF) at @var{x} of the exponential distribution with |
|
24 ## parameter @var{lambda}. |
3191
|
25 ## |
|
26 ## The arguments can be of common size or scalar. |
3456
|
27 ## @end deftypefn |
3426
|
28 |
3456
|
29 ## Author: KH <Kurt.Hornik@ci.tuwien.ac.at> |
|
30 ## Description: CDF of the exponential distribution |
3191
|
31 |
|
32 function cdf = exponential_cdf (x, l) |
3426
|
33 |
3191
|
34 if (nargin != 2) |
|
35 usage ("exponential_cdf (x, lambda)"); |
|
36 endif |
3426
|
37 |
4859
|
38 if (!isscalar (x) && !isscalar(l)) |
|
39 [retval, x, l] = common_size (x, l); |
|
40 if (retval > 0) |
|
41 error ("exponential_cdf: x and lambda must be of common size or scalar"); |
|
42 endif |
3191
|
43 endif |
3426
|
44 |
4859
|
45 if (isscalar (x)) |
|
46 sz = size (l); |
|
47 else |
|
48 sz = size (x); |
|
49 endif |
|
50 |
|
51 cdf = zeros (sz); |
3426
|
52 |
3191
|
53 k = find (isnan (x) | !(l > 0)); |
3456
|
54 if (any (k)) |
4859
|
55 cdf(k) = NaN; |
3191
|
56 endif |
3426
|
57 |
3191
|
58 k = find ((x == Inf) & (l > 0)); |
3456
|
59 if (any (k)) |
4859
|
60 cdf(k) = 1; |
3191
|
61 endif |
3426
|
62 |
3191
|
63 k = find ((x > 0) & (x < Inf) & (l > 0)); |
3456
|
64 if (any (k)) |
4859
|
65 if isscalar (l) |
|
66 cdf (k) = 1 - exp (- l .* x(k)); |
|
67 elseif isscalar (x) |
|
68 cdf (k) = 1 - exp (- l(k) .* x); |
|
69 else |
|
70 cdf (k) = 1 - exp (- l(k) .* x(k)); |
|
71 endif |
3191
|
72 endif |
|
73 |
|
74 endfunction |