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A C-program for MT19937, with initialization improved 2002/1/26.
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Coded by Takuji Nishimura and Makoto Matsumoto.
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Before using, initialize the state by using init_genrand(seed)
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or init_by_array(init_key, key_length).
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Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The names of its contributors may not be used to endorse or promote
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products derived from this software without specific prior written
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Any feedback is very welcome.
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http://www.math.keio.ac.jp/matumoto/emt.html
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email: matumoto@math.keio.ac.jp
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/* Period parameters */
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#define MATRIX_A 0x9908b0dfUL /* constant vector a */
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#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
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#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
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static unsigned long mt[N]; /* the array for the state vector */
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static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
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/* initializes mt[N] with a seed */
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void init_genrand(unsigned long s)
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mt[0]= s & 0xffffffffUL;
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for (mti=1; mti<N; mti++) {
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(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
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/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
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/* In the previous versions, MSBs of the seed affect */
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/* only MSBs of the array mt[]. */
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/* 2002/01/09 modified by Makoto Matsumoto */
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mt[mti] &= 0xffffffffUL;
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/* for >32 bit machines */
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/* initialize by an array with array-length */
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/* init_key is the array for initializing keys */
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/* key_length is its length */
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void init_by_array(init_key, key_length)
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unsigned long init_key[], key_length;
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init_genrand(19650218UL);
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k = (N>key_length ? N : key_length);
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mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
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+ init_key[j] + j; /* non linear */
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mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
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if (i>=N) { mt[0] = mt[N-1]; i=1; }
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if (j>=key_length) j=0;
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mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
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mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
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if (i>=N) { mt[0] = mt[N-1]; i=1; }
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mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
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/* generates a random number on [0,0xffffffff]-interval */
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unsigned long genrand_int32(void)
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static unsigned long mag01[2]={0x0UL, MATRIX_A};
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/* mag01[x] = x * MATRIX_A for x=0,1 */
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if (mti >= N) { /* generate N words at one time */
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if (mti == N+1) /* if init_genrand() has not been called, */
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init_genrand(5489UL); /* a default initial seed is used */
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for (kk=0;kk<N-M;kk++) {
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y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
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mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
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y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
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mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
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y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
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mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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/* generates a random number on [0,0x7fffffff]-interval */
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long genrand_int31(void)
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return (long)(genrand_int32()>>1);
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/* generates a random number on [0,1]-real-interval */
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double genrand_real1(void)
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return genrand_int32()*(1.0/4294967295.0);
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/* divided by 2^32-1 */
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/* generates a random number on [0,1)-real-interval */
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double genrand_real2(void)
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return genrand_int32()*(1.0/4294967296.0);
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/* divided by 2^32 */
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/* generates a random number on (0,1)-real-interval */
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double genrand_real3(void)
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return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0);
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/* divided by 2^32 */
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/* generates a random number on [0,1) with 53-bit resolution*/
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double genrand_res53(void)
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unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6;
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return(a*67108864.0+b)*(1.0/9007199254740992.0);
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/* These real versions are due to Isaku Wada, 2002/01/09 added */
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unsigned long init[4]={0x123, 0x234, 0x345, 0x456}, length=4;
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init_by_array(init, length);
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printf("1000 outputs of genrand_int32()\n");
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for (i=0; i<1000; i++) {
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printf("%10lu ", genrand_int32());
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if (i%5==4) printf("\n");
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printf("\n1000 outputs of genrand_real2()\n");
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for (i=0; i<1000; i++) {
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printf("%10.8f ", genrand_real2());
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if (i%5==4) printf("\n");
added
removed
src/mt19937ar.c
