REAL FUNCTION RNOR(JD)
C***BEGIN PROLOGUE  RNOR
C***DATE WRITTEN   810915
C***REVISION DATE  830805
C***CATEGORY NO.  L6A14
C***KEYWORDS  RANDOM NUMBERS, UNIFORM RANDOM NUMBERS
C***AUTHOR    KAHANER, DAVID, SCIENTIFIC COMPUTING DIVISION, NBS
C             MARSAGLIA, GEORGE, COMPUTER SCIENCE DEPT., WASH STATE UNIV
C
C***PURPOSE  GENERATES QUASI NORMAL RANDOM NUMBERS, WITH MEAN ZERO AND
C             UNIT STANDARD DEVIATION, AND CAN BE USED WITH ANY COMPUTER
C             WITH INTEGERS AT LEAST AS LARGE AS 32767.
C***DESCRIPTION
C
C       RNOR generates quasi normal random numbers with zero mean and
C       unit standard deviation.
C       It can be used with any computer with integers at least as
C       large as 32767.
C
C
C   Use
C       First time....
C                   Z = RNOR(JD)
C                     Here JD is any  n o n - z e r o  integer.
C                     This causes initialization of the program
C                     and the first random number to be returned as Z.
C       Subsequent times...
C                   Z = RNOR(0)
C                     Causes the next random number to be returned as Z.
C
C.....................................................................
C
C    Note: Users who wish to transport this program to other
C           computers should read the following ....
C
C   Machine dependencies...
C      MDIG = A lower bound on the number of binary digits available
C              for representing integers, including the sign bit.
C              This must be at least 16, but can be increased in
C              line with remark A below.
C
C   Remarks...
C     A. This program can be used in two ways:
C        (1) To obtain repeatable results on different computers,
C            set 'MDIG' to the smallest of its values on each, or,
C        (2) To allow the longest sequence of random numbers to be
C            generated without cycling (repeating) set 'MDIG' to the
C            largest possible value.
C     B. The sequence of numbers generated depends on the initial
C          input 'JD' as well as the value of 'MDIG'.
C          If MDIG=16 one should find that
C            the first evaluation
C              Z=RNOR(87) gives  Z=-.40079207...
C            The second evaluation
C              Z=RNOR(0) gives   Z=-1.8728870...
C            The third evaluation
C              Z=RNOR(0) gives   Z=1.8216004...
C            The fourth evaluation
C              Z=RNOR(0) gives   Z=.69410355...
C            The thousandth evaluation
C              Z=RNOR(0) gives   Z=.96782424...
C
C***REFERENCES  MARSAGLIA & TSANG, "A FAST, EASILY IMPLEMENTED
C                 METHOD FOR SAMPLING FROM DECREASING OR
C                 SYMMETRIC UNIMODAL DENSITY FUNCTIONS", TO BE
C                 PUBLISHED IN SIAM J SISC 1983.
C***ROUTINES CALLED  I1MACH,XERROR
C***END PROLOGUE  RNOR