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wims  3.65+svn20090927
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 
00011    Redistribution and use in source and binary forms, with or without
00012    modification, are permitted provided that the following conditions
00013    are met:
00014 
00015      1. Redistributions of source code must retain the above copyright
00016         notice, this list of conditions and the following disclaimer.
00017 
00018      2. Redistributions in binary form must reproduce the above copyright
00019         notice, this list of conditions and the following disclaimer in the
00020         documentation and/or other materials provided with the distribution.
00021 
00022      3. The names of its contributors may not be used to endorse or promote 
00023         products derived from this software without specific prior written 
00024         permission.
00025 
00026    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00027    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00028    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
00029    A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
00030    CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00031    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
00032    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00033    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00034    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00035    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00036    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00037 
00038 
00039    Any feedback is very welcome.
00040    http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
00041    email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
00042 */
00043 
00044 /* Period parameters */  
00045 #define N 624
00046 #define M 397
00047 #define MATRIX_A 0x9908b0dfUL   /* constant vector a */
00048 #define UPPER_MASK 0x80000000UL /* most significant w-r bits */
00049 #define LOWER_MASK 0x7fffffffUL /* least significant r bits */
00050 
00051 static unsigned long mt[N]; /* the array for the state vector  */
00052 static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
00053 
00054 /* initializes mt[N] with a seed */
00055 void init_genrand(unsigned long s)
00056 {
00057     mt[0]= s & 0xffffffffUL;
00058     for (mti=1; mti<N; mti++) {
00059         mt[mti] = 
00060            (1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti); 
00061         /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
00062         /* In the previous versions, MSBs of the seed affect   */
00063         /* only MSBs of the array mt[].                        */
00064         /* 2002/01/09 modified by Makoto Matsumoto             */
00065         mt[mti] &= 0xffffffffUL;
00066         /* for >32 bit machines */
00067     }
00068 }
00069 
00070 /* initialize by an array with array-length */
00071 /* init_key is the array for initializing keys */
00072 /* key_length is its length */
00073 /* slight change for C++, 2004/2/26 */
00074 void init_by_array(unsigned long init_key[], int key_length)
00075 {
00076     int i, j, k;
00077     init_genrand(19650218UL);
00078     i=1; j=0;
00079     k = (N>key_length ? N : key_length);
00080     for (; k; k--) {
00081         mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
00082           + init_key[j] + j; /* non linear */
00083         mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
00084         i++; j++;
00085         if (i>=N) { mt[0] = mt[N-1]; i=1; }
00086         if (j>=key_length) j=0;
00087     }
00088     for (k=N-1; k; k--) {
00089         mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
00090           - i; /* non linear */
00091         mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
00092         i++;
00093         if (i>=N) { mt[0] = mt[N-1]; i=1; }
00094     }
00095 
00096     mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ 
00097 }
00098 
00099 /* generates a random number on [0,0xffffffff]-interval */
00100 unsigned long genrand_int32(void)
00101 {
00102     unsigned long y;
00103     static unsigned long mag01[2]={0x0UL, MATRIX_A};
00104     /* mag01[x] = x * MATRIX_A  for x=0,1 */
00105 
00106     if (mti >= N) { /* generate N words at one time */
00107         int kk;
00108 
00109         if (mti == N+1)   /* if init_genrand() has not been called, */
00110             init_genrand(5489UL); /* a default initial seed is used */
00111 
00112         for (kk=0;kk<N-M;kk++) {
00113             y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
00114             mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
00115         }
00116         for (;kk<N-1;kk++) {
00117             y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
00118             mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
00119         }
00120         y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
00121         mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
00122 
00123         mti = 0;
00124     }
00125   
00126     y = mt[mti++];
00127 
00128     /* Tempering */
00129     y ^= (y >> 11);
00130     y ^= (y << 7) & 0x9d2c5680UL;
00131     y ^= (y << 15) & 0xefc60000UL;
00132     y ^= (y >> 18);
00133 
00134     return y;
00135 }
00136 
00137 /* generates a random number on [0,0x7fffffff]-interval */
00138 long genrand_int31(void)
00139 {
00140     return (long)(genrand_int32()>>1);
00141 }
00142 
00143 /* generates a random number on [0,1]-real-interval */
00144 double genrand_real1(void)
00145 {
00146     return genrand_int32()*(1.0/4294967295.0); 
00147     /* divided by 2^32-1 */ 
00148 }
00149 
00150 /* generates a random number on [0,1)-real-interval */
00151 double genrand_real2(void)
00152 {
00153     return genrand_int32()*(1.0/4294967296.0); 
00154     /* divided by 2^32 */
00155 }
00156 
00157 /* generates a random number on (0,1)-real-interval */
00158 double genrand_real3(void)
00159 {
00160     return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0); 
00161     /* divided by 2^32 */
00162 }
00163 
00164 /* generates a random number on [0,1) with 53-bit resolution*/
00165 double genrand_res53(void) 
00166 { 
00167     unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6; 
00168     return(a*67108864.0+b)*(1.0/9007199254740992.0); 
00169 } 
00170 /* These real versions are due to Isaku Wada, 2002/01/09 added */
00171