SUBROUTINE XDCON(X,IX)
C***BEGIN PROLOGUE  XDCON
C***DATE WRITTEN   820712   (YYMMDD)
C***REVISION DATE  831027   (YYMMDD)
C***CATEGORY NO.  A3d
C***KEYWORDS  EXTENDED-RANGE DOUBLE-PRECISION ARITHMETIC
C***AUTHOR  LOZIER, DANIEL W. (NATIONAL BUREAU OF STANDARDS)
C           SMITH, JOHN M. (NBS AND GEORGE MASON UNIVERSITY)
C***PURPOSE  TO PROVIDE DOUBLE-PRECISION FLOATING-POINT ARITHMETIC
C            WITH AN EXTENDED EXPONENT RANGE
C***DESCRIPTION
C     DOUBLE PRECISION X
C     INTEGER IX
C
C                  CONVERTS (X,IX) = X*RADIX**IX
C                  TO DECIMAL FORM IN PREPARATION FOR
C                  PRINTING, SO THAT (X,IX) = X*10**IX
C                  WHERE 1/10 .LE. ABS(X) .LT. 1
C                  IS RETURNED, EXCEPT THAT IF
C                  (DABS(X),IX) IS BETWEEN RADIX**(-2L)
C                  AND RADIX**(2L) THEN THE REDUCED
C                  FORM WITH IX = 0 IS RETURNED.
C
C***REFERENCES (PROGRAM LISTING FOR XDSET)
C***ROUTINES CALLED  XDADJ, XDC210, XDRED
C***COMMON BLOCKS    XDBLK2
C***END PROLOGUE  XDCON