ViewVC Help
View File | Revision Log | Show Annotations | View Changeset | Root Listing
root/group/trunk/OOPSE-4/src/math/MersenneTwister.hpp
Revision: 2759
Committed: Wed May 17 21:51:42 2006 UTC (18 years, 1 month ago) by tim
File size: 16419 byte(s)
Log Message:
Adding single precision capabilities to c++ side

File Contents

# Content
1 // 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 #include <vector>
70 namespace oopse {
71
72 class MTRand {
73 // Data
74 public:
75 typedef unsigned long uint32; // unsigned integer type, at least 32 bits
76
77 enum { N = 624 }; // length of state vector
78 enum { SAVE = N + 1 }; // length of array for save()
79
80 private:
81 enum { M = 397 }; // period parameter
82
83 uint32 state[N]; // internal state
84 uint32 *pNext; // next value to get from state
85 int left; // number of values left before reload needed
86 int nstrides_;
87 int stride_;
88
89 //Methods
90 public:
91 MTRand( const uint32& oneSeed, int nstrides, int stride); // initialize with a simple uint32
92 MTRand( uint32 *const bigSeed, uint32 const seedLength, int nstrides, int stride); // or an array
93 MTRand(int nstrides, int stride); // auto-initialize with /dev/urandom or time() and clock()
94
95 // Do NOT use for CRYPTOGRAPHY without securely hashing several returned
96 // values together, otherwise the generator state can be learned after
97 // reading 624 consecutive values.
98
99 // Access to 32-bit random numbers
100 RealType rand(); // real number in [0,1]
101 RealType rand( const RealType& n ); // real number in [0,n]
102 RealType randExc(); // real number in [0,1)
103 RealType randExc( const RealType& n ); // real number in [0,n)
104 RealType randDblExc(); // real number in (0,1)
105 RealType randDblExc( const RealType& n ); // real number in (0,n)
106 uint32 randInt(); // integer in [0,2^32-1] (modified for striding)
107 uint32 rawRandInt(); // original randInt
108 uint32 randInt( const uint32& n ); // integer in [0,n] for n < 2^32
109 RealType operator()() { return rand(); } // same as rand()
110
111 // Access to 53-bit random numbers (capacity of IEEE RealType precision)
112 RealType rand53(); // real number in [0,1)
113
114 // Access to nonuniform random number distributions
115 RealType randNorm( const RealType mean = 0.0, const RealType variance = 0.0 );
116
117 // Re-seeding functions with same behavior as initializers
118 void seed( const uint32 oneSeed );
119 void seed( uint32 *const bigSeed, const uint32 seedLength = N );
120 void seed();
121
122 std::vector<uint32>generateSeeds();
123
124 // Saving and loading generator state
125 void save( uint32* saveArray ) const; // to array of size SAVE
126 void load( uint32 *const loadArray ); // from such array
127 friend std::ostream& operator<<( std::ostream& os, const MTRand& mtrand );
128 friend std::istream& operator>>( std::istream& is, MTRand& mtrand );
129
130 protected:
131 void initialize( const uint32 oneSeed );
132 void reload();
133 uint32 hiBit( const uint32& u ) const { return u & 0x80000000UL; }
134 uint32 loBit( const uint32& u ) const { return u & 0x00000001UL; }
135 uint32 loBits( const uint32& u ) const { return u & 0x7fffffffUL; }
136 uint32 mixBits( const uint32& u, const uint32& v ) const
137 { return hiBit(u) | loBits(v); }
138 uint32 twist( const uint32& m, const uint32& s0, const uint32& s1 ) const
139 { return m ^ (mixBits(s0,s1)>>1) ^ (-loBit(s1) & 0x9908b0dfUL); }
140 static uint32 hash( time_t t, clock_t c );
141 };
142
143
144 inline MTRand::MTRand( const uint32& oneSeed, int nstrides, int stride) : nstrides_(nstrides), stride_(stride) {
145 assert(stride_ < nstrides_ && stride_ >= 0);
146 seed(oneSeed);
147 }
148
149 inline MTRand::MTRand( uint32 *const bigSeed, const uint32 seedLength, int nstrides, int stride) : nstrides_(nstrides), stride_(stride) {
150 assert(stride_ < nstrides_ && stride_ >= 0);
151 seed(bigSeed,seedLength);
152 }
153
154 inline MTRand::MTRand(int nstrides, int stride) : nstrides_(nstrides), stride_(stride){
155 assert(stride_ < nstrides_ && stride_ >= 0);
156 seed();
157 }
158
159 inline RealType MTRand::rand()
160 { return RealType(randInt()) * (1.0/4294967295.0); }
161
162 inline RealType MTRand::rand( const RealType& n )
163 { return rand() * n; }
164
165 inline RealType MTRand::randExc()
166 { return RealType(randInt()) * (1.0/4294967296.0); }
167
168 inline RealType MTRand::randExc( const RealType& n )
169 { return randExc() * n; }
170
171 inline RealType MTRand::randDblExc()
172 { return ( RealType(randInt()) + 0.5 ) * (1.0/4294967296.0); }
173
174 inline RealType MTRand::randDblExc( const RealType& n )
175 { return randDblExc() * n; }
176
177 inline RealType MTRand::rand53()
178 {
179 uint32 a = randInt() >> 5, b = randInt() >> 6;
180 return ( a * 67108864.0 + b ) * (1.0/9007199254740992.0); // by Isaku Wada
181 }
182
183 inline RealType MTRand::randNorm( const RealType mean, const RealType variance )
184 {
185 // Return a real number from a normal (Gaussian) distribution with given
186 // mean and variance by Box-Muller method
187 assert(variance > 0);
188 RealType r = sqrt( -2.0 * log( 1.0-randDblExc()) * variance);
189 RealType phi = 2.0 * 3.14159265358979323846264338328 * randExc();
190 return mean + r * cos(phi);
191 }
192
193 /**
194 * This function is modified from the original to allow for random
195 * streams on parallel jobs. It now takes numbers from by striding
196 * through the random stream and picking up only one of the random
197 * numbers per nstrides_. The number it picks is the stride_'th
198 * number in the stride sequence.
199 */
200 inline MTRand::uint32 MTRand::randInt() {
201
202 std::vector<uint32> ranNums(nstrides_);
203
204 for (int i = 0; i < nstrides_; ++i) {
205 ranNums[i] = rawRandInt();
206 }
207
208 return ranNums[stride_];
209 }
210
211 /**
212 * This is the original randInt function which implements the mersenne
213 * twister.
214 */
215 inline MTRand::uint32 MTRand::rawRandInt()
216 {
217 // Pull a 32-bit integer from the generator state
218 // Every other access function simply transforms the numbers extracted here
219
220 if( left == 0 ) reload();
221 --left;
222
223 register uint32 s1;
224 s1 = *pNext++;
225 s1 ^= (s1 >> 11);
226 s1 ^= (s1 << 7) & 0x9d2c5680UL;
227 s1 ^= (s1 << 15) & 0xefc60000UL;
228 return ( s1 ^ (s1 >> 18) );
229 }
230
231 inline MTRand::uint32 MTRand::randInt( const uint32& n )
232 {
233 // Find which bits are used in n
234 // Optimized by Magnus Jonsson (magnus@smartelectronix.com)
235 uint32 used = n;
236 used |= used >> 1;
237 used |= used >> 2;
238 used |= used >> 4;
239 used |= used >> 8;
240 used |= used >> 16;
241
242 // Draw numbers until one is found in [0,n]
243 uint32 i;
244 do
245 i = randInt() & used; // toss unused bits to shorten search
246 while( i > n );
247 return i;
248 }
249
250
251 inline void MTRand::seed( const uint32 oneSeed )
252 {
253 // Seed the generator with a simple uint32
254 initialize(oneSeed);
255 reload();
256 }
257
258
259 inline void MTRand::seed( uint32 *const bigSeed, const uint32 seedLength )
260 {
261 // Seed the generator with an array of uint32's
262 // There are 2^19937-1 possible initial states. This function allows
263 // all of those to be accessed by providing at least 19937 bits (with a
264 // default seed length of N = 624 uint32's). Any bits above the lower 32
265 // in each element are discarded.
266 // Just call seed() if you want to get array from /dev/urandom
267 initialize(19650218UL);
268 register int i = 1;
269 register uint32 j = 0;
270 register int k = ( N > seedLength ? N : seedLength );
271 for( ; k; --k )
272 {
273 state[i] =
274 state[i] ^ ( (state[i-1] ^ (state[i-1] >> 30)) * 1664525UL );
275 state[i] += ( bigSeed[j] & 0xffffffffUL ) + j;
276 state[i] &= 0xffffffffUL;
277 ++i; ++j;
278 if( i >= N ) { state[0] = state[N-1]; i = 1; }
279 if( j >= seedLength ) j = 0;
280 }
281 for( k = N - 1; k; --k )
282 {
283 state[i] =
284 state[i] ^ ( (state[i-1] ^ (state[i-1] >> 30)) * 1566083941UL );
285 state[i] -= i;
286 state[i] &= 0xffffffffUL;
287 ++i;
288 if( i >= N ) { state[0] = state[N-1]; i = 1; }
289 }
290 state[0] = 0x80000000UL; // MSB is 1, assuring non-zero initial array
291 reload();
292 }
293
294
295 inline void MTRand::seed()
296 {
297 std::vector<uint32> seeds;
298
299 seeds = generateSeeds();
300
301 if (seeds.size() == 1) {
302 seed( seeds[0] );
303 } else {
304 seed( &seeds[0], seeds.size() );
305 }
306 }
307
308
309 inline std::vector<MTRand::uint32> MTRand::generateSeeds() {
310 // Seed the generator with an array from /dev/urandom if available
311 // Otherwise use a hash of time() and clock() values
312
313 std::vector<uint32> bigSeed;
314
315 // First try getting an array from /dev/urandom
316 FILE* urandom = fopen( "/dev/urandom", "rb" );
317 if( urandom )
318 {
319 bigSeed.resize(N);
320 register uint32 *s = &bigSeed[0];
321 register int i = N;
322 register bool success = true;
323 while( success && i-- )
324 success = fread( s++, sizeof(uint32), 1, urandom );
325 fclose(urandom);
326 if( success ) { return bigSeed; }
327 }
328
329 // Was not successful, so use time() and clock() instead
330
331 bigSeed.push_back(hash( time(NULL), clock()));
332 return bigSeed;
333 }
334
335
336 inline void MTRand::initialize( const uint32 seed )
337 {
338 // Initialize generator state with seed
339 // See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
340 // In previous versions, most significant bits (MSBs) of the seed affect
341 // only MSBs of the state array. Modified 9 Jan 2002 by Makoto Matsumoto.
342 register uint32 *s = state;
343 register uint32 *r = state;
344 register int i = 1;
345 *s++ = seed & 0xffffffffUL;
346 for( ; i < N; ++i )
347 {
348 *s++ = ( 1812433253UL * ( *r ^ (*r >> 30) ) + i ) & 0xffffffffUL;
349 r++;
350 }
351 }
352
353
354 inline void MTRand::reload()
355 {
356 // Generate N new values in state
357 // Made clearer and faster by Matthew Bellew (matthew.bellew@home.com)
358 register uint32 *p = state;
359 register int i;
360 for( i = N - M; i--; ++p )
361 *p = twist( p[M], p[0], p[1] );
362 for( i = M; --i; ++p )
363 *p = twist( p[M-N], p[0], p[1] );
364 *p = twist( p[M-N], p[0], state[0] );
365
366 left = N, pNext = state;
367 }
368
369
370 inline MTRand::uint32 MTRand::hash( time_t t, clock_t c )
371 {
372 // Get a uint32 from t and c
373 // Better than uint32(x) in case x is floating point in [0,1]
374 // Based on code by Lawrence Kirby (fred@genesis.demon.co.uk)
375
376 static uint32 differ = 0; // guarantee time-based seeds will change
377
378 uint32 h1 = 0;
379 unsigned char *p = (unsigned char *) &t;
380 for( size_t i = 0; i < sizeof(t); ++i )
381 {
382 h1 *= UCHAR_MAX + 2U;
383 h1 += p[i];
384 }
385 uint32 h2 = 0;
386 p = (unsigned char *) &c;
387 for( size_t j = 0; j < sizeof(c); ++j )
388 {
389 h2 *= UCHAR_MAX + 2U;
390 h2 += p[j];
391 }
392 return ( h1 + differ++ ) ^ h2;
393 }
394
395
396 inline void MTRand::save( uint32* saveArray ) const
397 {
398 register uint32 *sa = saveArray;
399 register const uint32 *s = state;
400 register int i = N;
401 for( ; i--; *sa++ = *s++ ) {}
402 *sa = left;
403 }
404
405
406 inline void MTRand::load( uint32 *const loadArray )
407 {
408 register uint32 *s = state;
409 register uint32 *la = loadArray;
410 register int i = N;
411 for( ; i--; *s++ = *la++ ) {}
412 left = *la;
413 pNext = &state[N-left];
414 }
415
416
417 inline std::ostream& operator<<( std::ostream& os, const MTRand& mtrand )
418 {
419 register const MTRand::uint32 *s = mtrand.state;
420 register int i = mtrand.N;
421 for( ; i--; os << *s++ << "\t" ) {}
422 return os << mtrand.left;
423 }
424
425
426 inline std::istream& operator>>( std::istream& is, MTRand& mtrand )
427 {
428 register MTRand::uint32 *s = mtrand.state;
429 register int i = mtrand.N;
430 for( ; i--; is >> *s++ ) {}
431 is >> mtrand.left;
432 mtrand.pNext = &mtrand.state[mtrand.N-mtrand.left];
433 return is;
434 }
435
436 }
437 #endif // MERSENNETWISTER_H
438
439 // Change log:
440 //
441 // v0.1 - First release on 15 May 2000
442 // - Based on code by Makoto Matsumoto, Takuji Nishimura, and Shawn Cokus
443 // - Translated from C to C++
444 // - Made completely ANSI compliant
445 // - Designed convenient interface for initialization, seeding, and
446 // obtaining numbers in default or user-defined ranges
447 // - Added automatic seeding from /dev/urandom or time() and clock()
448 // - Provided functions for saving and loading generator state
449 //
450 // v0.2 - Fixed bug which reloaded generator one step too late
451 //
452 // v0.3 - Switched to clearer, faster reload() code from Matthew Bellew
453 //
454 // v0.4 - Removed trailing newline in saved generator format to be consistent
455 // with output format of built-in types
456 //
457 // v0.5 - Improved portability by replacing static const int's with enum's and
458 // clarifying return values in seed(); suggested by Eric Heimburg
459 // - Removed MAXINT constant; use 0xffffffffUL instead
460 //
461 // v0.6 - Eliminated seed overflow when uint32 is larger than 32 bits
462 // - Changed integer [0,n] generator to give better uniformity
463 //
464 // v0.7 - Fixed operator precedence ambiguity in reload()
465 // - Added access for real numbers in (0,1) and (0,n)
466 //
467 // v0.8 - Included time.h header to properly support time_t and clock_t
468 //
469 // v1.0 - Revised seeding to match 26 Jan 2002 update of Nishimura and Matsumoto
470 // - Allowed for seeding with arrays of any length
471 // - Added access for real numbers in [0,1) with 53-bit resolution
472 // - Added access for real numbers from normal (Gaussian) distributions
473 // - Increased overall speed by optimizing twist()
474 // - Doubled speed of integer [0,n] generation
475 // - Fixed out-of-range number generation on 64-bit machines
476 // - Improved portability by substituting literal constants for long enum's
477 // - Changed license from GNU LGPL to BSD