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1 | // This may look like C code, but it is really -*- C++ -*- |
2 | /* | |
3 | Copyright (C) 1988 Free Software Foundation | |
4 | written by Dirk Grunwald (grunwald@cs.uiuc.edu) | |
5 | ||
6 | This file is part of GNU CC. | |
7 | ||
8 | GNU CC is distributed in the hope that it will be useful, | |
9 | but WITHOUT ANY WARRANTY. No author or distributor | |
10 | accepts responsibility to anyone for the consequences of using it | |
11 | or for whether it serves any particular purpose or works at all, | |
12 | unless he says so in writing. Refer to the GNU CC General Public | |
13 | License for full details. | |
14 | ||
15 | Everyone is granted permission to copy, modify and redistribute | |
16 | GNU CC, but only under the conditions described in the | |
17 | GNU CC General Public License. A copy of this license is | |
18 | supposed to have been given to you along with GNU CC so you | |
19 | can know your rights and responsibilities. It should be in a | |
20 | file named COPYING. Among other things, the copyright notice | |
21 | and this notice must be preserved on all copies. | |
22 | */ | |
23 | #ifndef _Erlang_h | |
24 | #ifdef __GNUG__ | |
25 | #pragma once | |
26 | #pragma interface | |
27 | #endif | |
28 | #define _Erlang_h 1 | |
29 | ||
30 | #include <Random.h> | |
31 | ||
32 | class Erlang: public Random { | |
33 | protected: | |
34 | double pMean; | |
35 | double pVariance; | |
36 | int k; | |
37 | double a; | |
38 | void setState(); | |
39 | public: | |
40 | Erlang(double mean, double variance, RNG *gen); | |
41 | ||
42 | double mean(); | |
43 | double mean(double x); | |
44 | double variance(); | |
45 | double variance(double x); | |
46 | ||
47 | virtual double operator()(); | |
48 | ||
49 | }; | |
50 | ||
51 | #if defined(__OPTIMIZE__) || defined(USE_LIBGXX_INLINES) | |
52 | ||
53 | inline void Erlang::setState() { | |
54 | k = int( (pMean * pMean ) / pVariance + 0.5 ); | |
55 | k = (k > 0) ? k : 1; | |
56 | a = k / pMean; | |
57 | } | |
58 | ||
59 | inline Erlang::Erlang(double mean, double variance, RNG *gen) : (gen) | |
60 | { | |
61 | pMean = mean; pVariance = variance; | |
62 | setState(); | |
63 | } | |
64 | ||
65 | inline double Erlang::mean() { return pMean; } | |
66 | inline double Erlang::mean(double x) { | |
67 | double tmp = pMean; pMean = x; setState(); return tmp; | |
68 | }; | |
69 | ||
70 | inline double Erlang::variance() { return pVariance; } | |
71 | inline double Erlang::variance(double x) { | |
72 | double tmp = pVariance; pVariance = x; setState(); return tmp; | |
73 | } | |
74 | ||
75 | ||
76 | #endif | |
77 | #endif |