usr/src/lib/libF77/rand_.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *      @(#)rand_.c     5.4     5/13/90
 *
 * Routines to return random values
 *
 * calling sequence:
 *      double precision d, drand
 *      i = irand(iflag)
 *      x = rand(iflag)
 *      d = drand(iflag)
 * where:
 *      If arg is 1, generator is restarted. If arg is 0, next value
 *      is returned. Any other arg is a new seed for the generator.
 *      Integer values will range from 0 thru 2147483647.
 *      Real values will range from 0.0 thru 1.0
 *      (see rand(3))
 */

#if     defined(vax) || defined(tahoe) || defined(hp300)
#define RANDMAX         2147483647
#else   vax || tahoe
#if     pdp11
#define RANDMAX         32767
#else   pdp11
        UNKNOWN MACHINE!
#endif  pdp11
#endif  vax || tahoe

long irand_(iarg)
long *iarg;
{
        if (*iarg) srand((int)*iarg);
#if     pdp11
        return(( ((long)rand()) << 16) | rand());
#else   pdp11
        return( rand() );
#endif  pdp11
}

float rand_(iarg)
long *iarg;
{
        if (*iarg) srand((int)*iarg);
        return( (float)(rand())/(float)RANDMAX );
}

double drand_(iarg)
long *iarg;
{
        if (*iarg) srand((int)*iarg);
        return( (double)(rand())/(double)RANDMAX );
}