.Re: 一个随机数的问题 - 荔园在线 | 深圳大学学生论坛,荔园晨风BBS,深大在线网站

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发信人: Version (音乐，美的最初与最终), 信区: Program
标  题: Re: 一个随机数的问题
发信站: 荔园晨风BBS站 (Sun May 25 13:35:40 2003), 站内信件

是的。重复是个问题。但是我解决不了。
所以我找来了个程序给你。自己看下。也许对你有帮助的。

/*
* The authors of this software are Don Mitchell and Matt Blaze.
*              Copyright (c) 1995 by AT&T.
* Permission to use, copy, and modify this software without fee
* is hereby granted, provided that this entire notice is included in
* all copies of any software which is or includes a copy or
* modification of this software and in all copies of the supporting
* documentation for such software.
*
* This software may be subject to United States export controls.
*
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR AT&T MAKE ANY
* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
*/

#include <signal.h>
#include <setjmp.h>
#include <sys/time.h>
#include <math.h>
#include <stdio.h>

static jmp_buf env;
static unsigned count;
static unsigned ocount;
static unsigned buffer;

static int
tick()
{
        struct itimerval it, oit;

        timerclear(&it.it_interval);
        it.it_value.tv_sec = 0;
        it.it_value.tv_usec = 16665;
        if (setitimer(ITIMER_REAL, &it, &oit) < 0)
                perror("tick");
}

static void
interrupt()
{
        if (count)
                longjmp(env, 1);
        (void) signal(SIGALRM, interrupt);
        tick();
}

static unsigned long
roulette()
{

        if (setjmp(env)) {
                count ^= (count>>3) ^ (count>>6) ^ ocount;
                count &= 0x7;
                ocount=count;
                buffer = (buffer<<3) ^ count;
                return buffer;
        }
        (void) signal(SIGALRM, interrupt);
        count = 0;
        tick();
        for (;;)
                count++;        /* about 1 MHz on VAX 11/780 */
}

unsigned long
truerand()
{

        count=0;
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        (void) roulette();
        return roulette();

n_truerand(n)
int n;
{
        int slop, v;

        slop = 0x7FFFFFFF % n;
        do {
                v = truerand() >> 1;
        } while (v <= slop);
        return v % n;
}

--
                      *
          *                                  *
                          *             *
                      no more to say
                  ★     just wish you   ★
                            good luck

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