RANECU

The Random Number Generator RANECU is a FORTRAN application. RANECU produces uniform random numbers on [0,1]. RANECU is multiplicative linear congruential generator suitable for a 16-bit platform. It combines three simple generators, and has a period exceeding 81012.

It is constructed for more efficient use by providing for a sequence of random numbers and the numbers are returned in a single call. A set of three non-zero integer seeds can be supplied, failing which a default set is employed. If supplied, these three seeds, in order, should lie in the ranges [1,32362], [1,31726] and [1,31656] respectively.

SUBROUTINE RANECU (RVEC,LEN)

C Portable random number generator for 16 bit computer.

C Generates a sequence of LEN pseudo-random numbers, returned in

C RVEC.

DIMENSION RVEC(*)

SAVE ISEED1,ISEED2, ISEED3

DATA ISEED1,ISEED2,ISEED3/1234, 5678, 9876/

C Default values, used if none supplied via an ENTRY

C call at RECUIN

DO 100 I = 1,LEN

K=ISEED1/206

ISEED1 = 157*ISEED1-K*06) - K*1

IF(ISEED1.LT.0) ISEED1=ISEED1+32363

K=ISEED2/217

ISEED2 = 146*(ISEED2-K*217)-K*5

IF(ISEED2.LT.O) ISEED2=ISEED2+31727

K=ISEED3/222

ISEED3 = 142*(ISEED3-K*222)-K*133

IF(ISEED3.LT.0) ISEED3=ISEED3+31657

IZ=ISEED1-ISEED2

IF(IZ.GT.706)IZ = Z- 2362

IZ = 1Z+ISEED3

IF(IZ.LT.1)IZ = 1Z+32362

RVEC(I)=REAL(IZ)*3.0899E-5

100 CONTINUE

RETURN

ENTRY RECUIN(IS1, IS2, IS3)

ISEED1=IS1

ISEED2=IS2

ISEED3=IS3

RETURN

ENTRY RECUUT(IS1,IS2,IS3)

IS1=ISEED1

IS2=ISEED2

IS3=ISEED3

RETURN

END