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root/group/trunk/OOPSE-2.0/src/math/MersenneTwister.hpp
Revision: 2066
Committed: Tue Mar 1 15:26:13 2005 UTC (19 years, 4 months ago) by gezelter
File size: 15610 byte(s)
Log Message:
Making small modifications to allow for use on MPI machines

File Contents

# User Rev Content
1 tim 2064 // MersenneTwister.h
2     // Mersenne Twister random number generator -- a C++ class MTRand
3     // Based on code by Makoto Matsumoto, Takuji Nishimura, and Shawn Cokus
4     // Richard J. Wagner v1.0 15 May 2003 rjwagner@writeme.com
5    
6     // The Mersenne Twister is an algorithm for generating random numbers. It
7     // was designed with consideration of the flaws in various other generators.
8     // The period, 2^19937-1, and the order of equidistribution, 623 dimensions,
9     // are far greater. The generator is also fast; it avoids multiplication and
10     // division, and it benefits from caches and pipelines. For more information
11     // see the inventors' web page at http://www.math.keio.ac.jp/~matumoto/emt.html
12    
13     // Reference
14     // M. Matsumoto and T. Nishimura, "Mersenne Twister: A 623-Dimensionally
15     // Equidistributed Uniform Pseudo-Random Number Generator", ACM Transactions on
16     // Modeling and Computer Simulation, Vol. 8, No. 1, January 1998, pp 3-30.
17    
18     // Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
19     // Copyright (C) 2000 - 2003, Richard J. Wagner
20     // All rights reserved.
21     //
22     // Redistribution and use in source and binary forms, with or without
23     // modification, are permitted provided that the following conditions
24     // are met:
25     //
26     // 1. Redistributions of source code must retain the above copyright
27     // notice, this list of conditions and the following disclaimer.
28     //
29     // 2. Redistributions in binary form must reproduce the above copyright
30     // notice, this list of conditions and the following disclaimer in the
31     // documentation and/or other materials provided with the distribution.
32     //
33     // 3. The names of its contributors may not be used to endorse or promote
34     // products derived from this software without specific prior written
35     // permission.
36     //
37     // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
38     // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
39     // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
40     // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
41     // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
42     // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
43     // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
44     // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
45     // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
46     // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
47     // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
48    
49     // The original code included the following notice:
50     //
51     // When you use this, send an email to: matumoto@math.keio.ac.jp
52     // with an appropriate reference to your work.
53     //
54     // It would be nice to CC: rjwagner@writeme.com and Cokus@math.washington.edu
55     // when you write.
56    
57     #ifndef MERSENNETWISTER_H
58     #define MERSENNETWISTER_H
59    
60     // Not thread safe (unless auto-initialization is avoided and each thread has
61     // its own MTRand object)
62    
63     #include <cassert>
64     #include <iostream>
65     #include <limits.h>
66     #include <stdio.h>
67     #include <time.h>
68     #include <math.h>
69    
70     class MTRand {
71     // Data
72     public:
73     typedef unsigned long uint32; // unsigned integer type, at least 32 bits
74    
75     enum { N = 624 }; // length of state vector
76     enum { SAVE = N + 1 }; // length of array for save()
77    
78     private:
79     enum { M = 397 }; // period parameter
80    
81     uint32 state[N]; // internal state
82     uint32 *pNext; // next value to get from state
83     int left; // number of values left before reload needed
84     int nstrides_;
85     int stride_;
86    
87     //Methods
88     public:
89 tim 2065 MTRand( const uint32& oneSeed, int nstrides = 1, int stride = 0); // initialize with a simple uint32
90     MTRand( uint32 *const bigSeed, uint32 const seedLength = N, int nstrides = 1, int stride = 0); // or an array
91     MTRand(int nstrides = 1, int stride = 0); // auto-initialize with /dev/urandom or time() and clock()
92 tim 2064
93     // Do NOT use for CRYPTOGRAPHY without securely hashing several returned
94     // values together, otherwise the generator state can be learned after
95     // reading 624 consecutive values.
96    
97     // Access to 32-bit random numbers
98     double rand(); // real number in [0,1]
99     double rand( const double& n ); // real number in [0,n]
100     double randExc(); // real number in [0,1)
101     double randExc( const double& n ); // real number in [0,n)
102     double randDblExc(); // real number in (0,1)
103     double randDblExc( const double& n ); // real number in (0,n)
104 gezelter 2066 uint32 randInt(); // integer in [0,2^32-1] (modified for striding)
105     uint32 rawRandInt(); // original randInt
106 tim 2064 uint32 randInt( const uint32& n ); // integer in [0,n] for n < 2^32
107     double operator()() { return rand(); } // same as rand()
108    
109     // Access to 53-bit random numbers (capacity of IEEE double precision)
110     double rand53(); // real number in [0,1)
111    
112     // Access to nonuniform random number distributions
113     double randNorm( const double& mean = 0.0, const double& variance = 0.0 );
114    
115     // Re-seeding functions with same behavior as initializers
116     void seed( const uint32 oneSeed );
117     void seed( uint32 *const bigSeed, const uint32 seedLength = N );
118     void seed();
119    
120     // Saving and loading generator state
121     void save( uint32* saveArray ) const; // to array of size SAVE
122     void load( uint32 *const loadArray ); // from such array
123     friend std::ostream& operator<<( std::ostream& os, const MTRand& mtrand );
124     friend std::istream& operator>>( std::istream& is, MTRand& mtrand );
125    
126     protected:
127     void initialize( const uint32 oneSeed );
128     void reload();
129     uint32 hiBit( const uint32& u ) const { return u & 0x80000000UL; }
130     uint32 loBit( const uint32& u ) const { return u & 0x00000001UL; }
131     uint32 loBits( const uint32& u ) const { return u & 0x7fffffffUL; }
132     uint32 mixBits( const uint32& u, const uint32& v ) const
133     { return hiBit(u) | loBits(v); }
134     uint32 twist( const uint32& m, const uint32& s0, const uint32& s1 ) const
135     { return m ^ (mixBits(s0,s1)>>1) ^ (-loBit(s1) & 0x9908b0dfUL); }
136     static uint32 hash( time_t t, clock_t c );
137     };
138    
139    
140     inline MTRand::MTRand( const uint32& oneSeed, int nstrides, int stride) : nstrides_(nstrides), stride_(stride) {
141     assert(stride_ < nstrides_ && stride_ >= 0);
142     seed(oneSeed);
143     }
144    
145     inline MTRand::MTRand( uint32 *const bigSeed, const uint32 seedLength, int nstrides, int stride) : nstrides_(nstrides), stride_(stride) {
146     assert(stride_ < nstrides_ && stride_ >= 0);
147     seed(bigSeed,seedLength);
148     }
149    
150     inline MTRand::MTRand(int nstrides, int stride) : nstrides_(nstrides), stride_(stride){
151     assert(stride_ < nstrides_ && stride_ >= 0);
152     seed();
153     }
154    
155     inline double MTRand::rand()
156     { return double(randInt()) * (1.0/4294967295.0); }
157    
158     inline double MTRand::rand( const double& n )
159     { return rand() * n; }
160    
161     inline double MTRand::randExc()
162     { return double(randInt()) * (1.0/4294967296.0); }
163    
164     inline double MTRand::randExc( const double& n )
165     { return randExc() * n; }
166    
167     inline double MTRand::randDblExc()
168     { return ( double(randInt()) + 0.5 ) * (1.0/4294967296.0); }
169    
170     inline double MTRand::randDblExc( const double& n )
171     { return randDblExc() * n; }
172    
173     inline double MTRand::rand53()
174     {
175     uint32 a = randInt() >> 5, b = randInt() >> 6;
176     return ( a * 67108864.0 + b ) * (1.0/9007199254740992.0); // by Isaku Wada
177     }
178    
179     inline double MTRand::randNorm( const double& mean, const double& variance )
180     {
181     // Return a real number from a normal (Gaussian) distribution with given
182     // mean and variance by Box-Muller method
183     double r = sqrt( -2.0 * log( 1.0-randDblExc()) ) * variance;
184     double phi = 2.0 * 3.14159265358979323846264338328 * randExc();
185     return mean + r * cos(phi);
186     }
187    
188 gezelter 2066 /**
189     * This function is modified from the original to allow for random
190     * streams on parallel jobs. It now takes numbers from by striding
191     * through the random stream and picking up only one of the random
192     * numbers per nstrides_. The number it picks is the stride_'th
193     * number in the stride sequence.
194     */
195     inline MTRand::uint32 MTRand::randInt() {
196    
197     uint32 ranNums[nstrides_];
198    
199     for (int i = 0; i < nstrides_; ++i) {
200     ranNums[i] = rawRandInt();
201     }
202    
203     return ranNums[stride_];
204     }
205    
206     /**
207     * This is the original randInt function which implements the mersenne
208     * twister.
209     */
210     inline MTRand::uint32 MTRand::rawRandInt()
211 tim 2064 {
212     // Pull a 32-bit integer from the generator state
213     // Every other access function simply transforms the numbers extracted here
214 gezelter 2066
215     if( left == 0 ) reload();
216     --left;
217    
218     register uint32 s1;
219     s1 = *pNext++;
220     s1 ^= (s1 >> 11);
221     s1 ^= (s1 << 7) & 0x9d2c5680UL;
222     s1 ^= (s1 << 15) & 0xefc60000UL;
223     return ( s1 ^ (s1 >> 18) );
224 tim 2064 }
225    
226     inline MTRand::uint32 MTRand::randInt( const uint32& n )
227     {
228     // Find which bits are used in n
229     // Optimized by Magnus Jonsson (magnus@smartelectronix.com)
230     uint32 used = n;
231     used |= used >> 1;
232     used |= used >> 2;
233     used |= used >> 4;
234     used |= used >> 8;
235     used |= used >> 16;
236    
237     // Draw numbers until one is found in [0,n]
238     uint32 i;
239     do
240     i = randInt() & used; // toss unused bits to shorten search
241     while( i > n );
242     return i;
243     }
244    
245    
246     inline void MTRand::seed( const uint32 oneSeed )
247     {
248     // Seed the generator with a simple uint32
249     initialize(oneSeed);
250     reload();
251     }
252    
253    
254     inline void MTRand::seed( uint32 *const bigSeed, const uint32 seedLength )
255     {
256     // Seed the generator with an array of uint32's
257     // There are 2^19937-1 possible initial states. This function allows
258     // all of those to be accessed by providing at least 19937 bits (with a
259     // default seed length of N = 624 uint32's). Any bits above the lower 32
260     // in each element are discarded.
261     // Just call seed() if you want to get array from /dev/urandom
262     initialize(19650218UL);
263     register int i = 1;
264     register uint32 j = 0;
265     register int k = ( N > seedLength ? N : seedLength );
266     for( ; k; --k )
267     {
268     state[i] =
269     state[i] ^ ( (state[i-1] ^ (state[i-1] >> 30)) * 1664525UL );
270     state[i] += ( bigSeed[j] & 0xffffffffUL ) + j;
271     state[i] &= 0xffffffffUL;
272     ++i; ++j;
273     if( i >= N ) { state[0] = state[N-1]; i = 1; }
274     if( j >= seedLength ) j = 0;
275     }
276     for( k = N - 1; k; --k )
277     {
278     state[i] =
279     state[i] ^ ( (state[i-1] ^ (state[i-1] >> 30)) * 1566083941UL );
280     state[i] -= i;
281     state[i] &= 0xffffffffUL;
282     ++i;
283     if( i >= N ) { state[0] = state[N-1]; i = 1; }
284     }
285     state[0] = 0x80000000UL; // MSB is 1, assuring non-zero initial array
286     reload();
287     }
288    
289    
290     inline void MTRand::seed()
291     {
292 gezelter 2066 vector<uint32> seeds;
293    
294     seeds = generateSeeds();
295    
296     if (seeds.size() == 1) {
297     seed( seeds[0] );
298     } else {
299     seed( &seeds[0], seeds.size() );
300     }
301 tim 2064 }
302    
303    
304 gezelter 2066 inline vector<uint32> MTRand::generateSeeds() {
305     // Seed the generator with an array from /dev/urandom if available
306     // Otherwise use a hash of time() and clock() values
307    
308     vector<uint32> bigSeed;
309    
310     // First try getting an array from /dev/urandom
311     FILE* urandom = fopen( "/dev/urandom", "rb" );
312     if( urandom )
313     {
314     bigSeed.resize(N);
315     register uint32 *s = &bigSeed[0];
316     register int i = N;
317     register bool success = true;
318     while( success && i-- )
319     success = fread( s++, sizeof(uint32), 1, urandom );
320     fclose(urandom);
321     if( success ) { return bigSeed; }
322     }
323    
324     // Was not successful, so use time() and clock() instead
325    
326     bigSeed.push_back(hash( time(NULL), clock()));
327     return bigSeed;
328     }
329    
330    
331 tim 2064 inline void MTRand::initialize( const uint32 seed )
332     {
333     // Initialize generator state with seed
334     // See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
335     // In previous versions, most significant bits (MSBs) of the seed affect
336     // only MSBs of the state array. Modified 9 Jan 2002 by Makoto Matsumoto.
337     register uint32 *s = state;
338     register uint32 *r = state;
339     register int i = 1;
340     *s++ = seed & 0xffffffffUL;
341     for( ; i < N; ++i )
342     {
343     *s++ = ( 1812433253UL * ( *r ^ (*r >> 30) ) + i ) & 0xffffffffUL;
344     r++;
345     }
346     }
347    
348    
349     inline void MTRand::reload()
350     {
351     // Generate N new values in state
352     // Made clearer and faster by Matthew Bellew (matthew.bellew@home.com)
353     register uint32 *p = state;
354     register int i;
355     for( i = N - M; i--; ++p )
356     *p = twist( p[M], p[0], p[1] );
357     for( i = M; --i; ++p )
358     *p = twist( p[M-N], p[0], p[1] );
359     *p = twist( p[M-N], p[0], state[0] );
360    
361     left = N, pNext = state;
362     }
363    
364    
365     inline MTRand::uint32 MTRand::hash( time_t t, clock_t c )
366     {
367     // Get a uint32 from t and c
368     // Better than uint32(x) in case x is floating point in [0,1]
369     // Based on code by Lawrence Kirby (fred@genesis.demon.co.uk)
370    
371     static uint32 differ = 0; // guarantee time-based seeds will change
372    
373     uint32 h1 = 0;
374     unsigned char *p = (unsigned char *) &t;
375     for( size_t i = 0; i < sizeof(t); ++i )
376     {
377     h1 *= UCHAR_MAX + 2U;
378     h1 += p[i];
379     }
380     uint32 h2 = 0;
381     p = (unsigned char *) &c;
382     for( size_t j = 0; j < sizeof(c); ++j )
383     {
384     h2 *= UCHAR_MAX + 2U;
385     h2 += p[j];
386     }
387     return ( h1 + differ++ ) ^ h2;
388     }
389    
390    
391     inline void MTRand::save( uint32* saveArray ) const
392     {
393     register uint32 *sa = saveArray;
394     register const uint32 *s = state;
395     register int i = N;
396     for( ; i--; *sa++ = *s++ ) {}
397     *sa = left;
398     }
399    
400    
401     inline void MTRand::load( uint32 *const loadArray )
402     {
403     register uint32 *s = state;
404     register uint32 *la = loadArray;
405     register int i = N;
406     for( ; i--; *s++ = *la++ ) {}
407     left = *la;
408     pNext = &state[N-left];
409     }
410    
411    
412     inline std::ostream& operator<<( std::ostream& os, const MTRand& mtrand )
413     {
414     register const MTRand::uint32 *s = mtrand.state;
415     register int i = mtrand.N;
416     for( ; i--; os << *s++ << "\t" ) {}
417     return os << mtrand.left;
418     }
419    
420    
421     inline std::istream& operator>>( std::istream& is, MTRand& mtrand )
422     {
423     register MTRand::uint32 *s = mtrand.state;
424     register int i = mtrand.N;
425     for( ; i--; is >> *s++ ) {}
426     is >> mtrand.left;
427     mtrand.pNext = &mtrand.state[mtrand.N-mtrand.left];
428     return is;
429     }
430    
431     #endif // MERSENNETWISTER_H
432    
433     // Change log:
434     //
435     // v0.1 - First release on 15 May 2000
436     // - Based on code by Makoto Matsumoto, Takuji Nishimura, and Shawn Cokus
437     // - Translated from C to C++
438     // - Made completely ANSI compliant
439     // - Designed convenient interface for initialization, seeding, and
440     // obtaining numbers in default or user-defined ranges
441     // - Added automatic seeding from /dev/urandom or time() and clock()
442     // - Provided functions for saving and loading generator state
443     //
444     // v0.2 - Fixed bug which reloaded generator one step too late
445     //
446     // v0.3 - Switched to clearer, faster reload() code from Matthew Bellew
447     //
448     // v0.4 - Removed trailing newline in saved generator format to be consistent
449     // with output format of built-in types
450     //
451     // v0.5 - Improved portability by replacing static const int's with enum's and
452     // clarifying return values in seed(); suggested by Eric Heimburg
453     // - Removed MAXINT constant; use 0xffffffffUL instead
454     //
455     // v0.6 - Eliminated seed overflow when uint32 is larger than 32 bits
456     // - Changed integer [0,n] generator to give better uniformity
457     //
458     // v0.7 - Fixed operator precedence ambiguity in reload()
459     // - Added access for real numbers in (0,1) and (0,n)
460     //
461     // v0.8 - Included time.h header to properly support time_t and clock_t
462     //
463     // v1.0 - Revised seeding to match 26 Jan 2002 update of Nishimura and Matsumoto
464     // - Allowed for seeding with arrays of any length
465     // - Added access for real numbers in [0,1) with 53-bit resolution
466     // - Added access for real numbers from normal (Gaussian) distributions
467     // - Increased overall speed by optimizing twist()
468     // - Doubled speed of integer [0,n] generation
469     // - Fixed out-of-range number generation on 64-bit machines
470     // - Improved portability by substituting literal constants for long enum's
471     // - Changed license from GNU LGPL to BSD