88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
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//random.cpp
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//random number generator
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#include <stdlib.h>
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#include <time.h>
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#include <math.h>
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/* A C-program for TT800 : July 8th 1996 Version */
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/* by M. Matsumoto, email: matumoto@math.keio.ac.jp */
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/* genrand() generate one pseudorandom number with double precision */
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/* which is uniformly distributed on [0,1]-interval */
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/* for each call. One may choose any initial 25 seeds */
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/* except all zeros. */
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/* See: ACM Transactions on Modelling and Computer Simulation, */
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/* Vol. 4, No. 3, 1994, pages 254-266. */
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#define N 25
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#define M 7
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unsigned long x[N]; /* initial 25 seeds, change as you wish */
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double genrand()
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{
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unsigned long y;
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static int k = 0;
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static unsigned long mag01[2]={
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0x0, 0x8ebfd028 /* this is magic vector `a', don't change */
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};
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if (k==N) { /* generate N words at one time */
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int kk;
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for (kk=0;kk<N-M;kk++) {
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x[kk] = x[kk+M] ^ (x[kk] >> 1) ^ mag01[x[kk] % 2];
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}
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for (; kk<N;kk++) {
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x[kk] = x[kk+(M-N)] ^ (x[kk] >> 1) ^ mag01[x[kk] % 2];
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}
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k=0;
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}
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y = x[k];
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y ^= (y << 7) & 0x2b5b2500; /* s and b, magic vectors */
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y ^= (y << 15) & 0xdb8b0000; /* t and c, magic vectors */
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y &= 0xffffffff; /* you may delete this line if word size = 32 */
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/*
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the following line was added by Makoto Matsumoto in the 1996 version
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to improve lower bit's corellation.
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Delete this line to o use the code published in 1994.
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*/
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y ^= (y >> 16); /* added to the 1994 version */
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k++;
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return( (double) y / (unsigned long) 0xffffffff);
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}
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//APIs to use genrand function
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void RandomInit()
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//Inits the random seeds using the standard C rand() function
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{
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int i;
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time_t t;
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time(&t);
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srand(t);
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for(i=0;i<N;i++)
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x[i]=rand();
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}
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float RandomFl(float min,float max)
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//gives a random float evenly distibuted in the intervall [min,max]
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{
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return genrand()*(max-min)+min;
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}
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int RandomInt(int min,int max)
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//gives a random int evenly distributed in the intervall [min,max-1]
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{
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double ran;
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do ran=genrand(); while(ran==1);
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return floor(ran*(max-min)+min);
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}
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int RandomProb(float prob)
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//returns true with a probility of prob
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//(ie. if prob is 1 always returns true, if prob is 0 always returns false)
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{
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return genrand()<=prob;
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}
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