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mt19937ar.c

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00001 //
00002 // A C-program for MT19937, with initialization improved 2002/1/26.
00003 // Coded by Takuji Nishimura and Makoto Matsumoto.
00004 //
00005 // Before using, initialize the state by using init_genrand(seed)
00006 // or init_by_array(init_key, key_length).
00007 //
00008 // Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
00009 // All rights reserved.
00010 // Copyright (C) 2005, Mutsuo Saito,
00011 // All rights reserved.
00012 //
00013 // Redistribution and use in source and binary forms, with or without
00014 // modification, are permitted provided that the following conditions
00015 // are met:
00016 //
00017 //   1. Redistributions of source code must retain the above copyright
00018 //      notice, this list of conditions and the following disclaimer.
00019 //
00020 //   2. Redistributions in binary form must reproduce the above copyright
00021 //      notice, this list of conditions and the following disclaimer in the
00022 //      documentation and/or other materials provided with the distribution.
00023 //
00024 //   3. The names of its contributors may not be used to endorse or promote
00025 //      products derived from this software without specific prior written
00026 //      permission.
00027 //
00028 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00029 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00030 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
00031 // A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
00032 // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00033 // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
00034 // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00035 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00036 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00037 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00038 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00039 //
00040 //
00041 // Any feedback is very welcome.
00042 // http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
00043 // email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
00044 //
00045 
00046 #include <stdio.h>
00047 #include "mt19937ar.h"
00048 
00049 // Period parameters
00050 #define N             624
00051 #define M             397
00052 #define MATRIX_A      0x9908b0dfUL // constant vector a
00053 #define UPPER_MASK    0x80000000UL // most significant w-r bits
00054 #define LOWER_MASK    0x7fffffffUL // least significant r bits
00055 
00056 static unsigned long mt[N];        // the array for the state vector
00057 static int           mti = N + 1;  // mti==N+1 means mt[N] is not initialized
00058 
00059 // initializes mt[N] with a seed
00060 void init_genrand( unsigned long s )
00061 {
00062     mt[0] = s & 0xffffffffUL;
00063     for ( mti = 1; mti < N; mti++ )
00064     {
00065         mt[mti] =
00066             ( 1812433253UL * ( mt[mti - 1] ^ ( mt[mti - 1] >> 30 ) ) + mti );
00067         // See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier.
00068         // In the previous versions, MSBs of the seed affect
00069         // only MSBs of the array mt[].
00070         // 2002/01/09 modified by Makoto Matsumoto
00071         mt[mti] &= 0xffffffffUL;
00072         // for >32 bit machines
00073     }
00074 }
00075 
00076 // initialize by an array with array-length
00077 // init_key is the array for initializing keys
00078 // key_length is its length
00079 // slight change for C++, 2004/2/26
00080 void init_by_array( unsigned long init_key[], int key_length )
00081 {
00082     int i, j, k;
00083     init_genrand( 19650218UL );
00084     i = 1; j = 0;
00085     k = ( N > key_length ? N : key_length );
00086     for (; k; k-- )
00087     {
00088         mt[i] = ( mt[i] ^ ( ( mt[i - 1] ^ ( mt[i - 1] >> 30 ) ) * 1664525UL ) )
00089                 + init_key[j] + j; // non linear
00090         mt[i] &= 0xffffffffUL;     // for WORDSIZE > 32 machines
00091         i++; j++;
00092         if ( i >= N )
00093         {
00094             mt[0] = mt[N - 1]; i = 1;
00095         }
00096         if ( j >= key_length )
00097             j = 0;
00098     }
00099     for ( k = N - 1; k; k-- )
00100     {
00101         mt[i] = ( mt[i] ^ ( ( mt[i - 1] ^ ( mt[i - 1] >> 30 ) ) * 1566083941UL ) )
00102                 - i;           // non linear
00103         mt[i] &= 0xffffffffUL; // for WORDSIZE > 32 machines
00104         i++;
00105         if ( i >= N )
00106         {
00107             mt[0] = mt[N - 1]; i = 1;
00108         }
00109     }
00110 
00111     mt[0] = 0x80000000UL; // MSB is 1; assuring non-zero initial array
00112 }
00113 
00114 // generates a random number on [0,0xffffffff]-interval
00115 unsigned long genrand_int32( void )
00116 {
00117     unsigned long        y;
00118     static unsigned long mag01[2] = { 0x0UL, MATRIX_A };
00119     // mag01[x] = x * MATRIX_A  for x=0,1
00120 
00121     if ( mti >= N )   // generate N words at one time
00122     {
00123         int kk;
00124 
00125         if ( mti == N + 1 )         // if init_genrand() has not been called,
00126             init_genrand( 5489UL ); // a default initial seed is used
00127 
00128         for ( kk = 0; kk < N - M; kk++ )
00129         {
00130             y      = ( mt[kk] & UPPER_MASK ) | ( mt[kk + 1] & LOWER_MASK );
00131             mt[kk] = mt[kk + M] ^ ( y >> 1 ) ^ mag01[y & 0x1UL];
00132         }
00133         for (; kk < N - 1; kk++ )
00134         {
00135             y      = ( mt[kk] & UPPER_MASK ) | ( mt[kk + 1] & LOWER_MASK );
00136             mt[kk] = mt[kk + ( M - N )] ^ ( y >> 1 ) ^ mag01[y & 0x1UL];
00137         }
00138         y         = ( mt[N - 1] & UPPER_MASK ) | ( mt[0] & LOWER_MASK );
00139         mt[N - 1] = mt[M - 1] ^ ( y >> 1 ) ^ mag01[y & 0x1UL];
00140 
00141         mti = 0;
00142     }
00143 
00144     y = mt[mti++];
00145 
00146     // Tempering
00147     y ^= ( y >> 11 );
00148     y ^= ( y << 7 ) & 0x9d2c5680UL;
00149     y ^= ( y << 15 ) & 0xefc60000UL;
00150     y ^= ( y >> 18 );
00151 
00152     return y;
00153 }
00154 
00155 // generates a random number on [0,0x7fffffff]-interval
00156 long genrand_int31( void )
00157 {
00158     return (long) ( genrand_int32() >> 1 );
00159 }
00160 
00161 // generates a random number on [0,1]-real-interval
00162 double genrand_real1( void )
00163 {
00164     return genrand_int32() * ( 1.0 / 4294967295.0 );
00165     // divided by 2^32-1
00166 }
00167 
00168 // generates a random number on [0,1)-real-interval
00169 double genrand_real2( void )
00170 {
00171     return genrand_int32() * ( 1.0 / 4294967296.0 );
00172     // divided by 2^32
00173 }
00174 
00175 // generates a random number on (0,1)-real-interval
00176 double genrand_real3( void )
00177 {
00178     return ( ( (double) genrand_int32() ) + 0.5 ) * ( 1.0 / 4294967296.0 );
00179     // divided by 2^32
00180 }
00181 
00182 // generates a random number on [0,1) with 53-bit resolution
00183 double genrand_res53( void )
00184 {
00185     unsigned long a = genrand_int32() >> 5, b = genrand_int32() >> 6;
00186     return ( a * 67108864.0 + b ) * ( 1.0 / 9007199254740992.0 );
00187 }
00188 // These real versions are due to Isaku Wada, 2002/01/09 added

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