Re: CCL:random no.generation(doubt)

 hello,
 A random number generator with very little remaining structure in the
 result of consecutive calls may look like this:
       function ggubs()
 cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
 c
 c  ggubs
 c
 c
 c  purpose             - basic uniform (0,1) pseudo-random number
 c                        generator
 c  arguments    dseed  - input/output double precision variable
 c                        assigned an integer value in the
 c                        exclusive range (1.d0, 2147483647.d0).
 c                        dseed is replaced by a new value to be
 c                        used in a subsequent call.
 c
 c
       real*8 dseed,c1,c2,ggubs,c3
       include 'mpif.h'
       parameter (c1=2147483647.d+00,c2=2.d+00**(-31),ic3=16807)
       common/random/dseed
       dseed=dmod(ic3*dseed,c1)
       ggubs=c2*dseed
       i=i+1
     5 format(d30.20)
       return
       end
 where dmod(x,y) does the following:
 DMOD
 DMOD calculates a longreal number modulus a second longreal number.
 Declaration
         FUNCTION DMOD(VAR x,y:LONGREAL):LONGREAL; EXTERNAL;
 Attributes
 Parameters:               Both arguments are longreal numbers.
 Result:                   A longreal number.
 HP FORTRAN 77/XL:         Intrinsic function:  Z=DMOD(X,Y).
 Error:                    If either of the arguments is a NaN (or the
                           first argument is infinity or the second
                           argument is zero), there are two possible
                           actions.  If the INVALID trap is enabled, the
                           message "DMOD(X,Y): ANY OF X AND Y=NaN OR
                           X=INFINITY OR Y=0.0" occurs.  Otherwise, the
                           INVALID flag is set.  In either case, a quiet
                           NaN is returned.
 This was tested in the context of phase space sampling for molecular
 dynamics simulations by some folks in Göteborg like 10 years ago
 (I havn't got the exact reference at arms length, sorry) and it has
 been used ever since.
 for what it's worth ;-)
 /Harald
 On Mon, 30 Sep 2002, sweta nigam wrote:
 > hello
 > can u help me to find out what r random no.generators ,plz site some
 examples used in commercial software like tripos or accelrys in their molecular
 dyanamics suite...
 >
 > Thanks n Regards
 > Sweta
 > TCS
 >
 Dr. Harald Svedung                       cellphone: +49-175 736 2576
 Institut für Physikalische Chemie               or: +46-709-223 206
 Universität Karlsruhe
 Fritz-Haber-Weg 4
 D-761 28  Karlsruhe
 Tyskland
 Tel: +49-721 608 2715
 Fax:+49-721 608 6524