SLATEC Routines --- ZS1S2 ---

*DECK ZS1S2
      SUBROUTINE ZS1S2 (ZRR, ZRI, S1R, S1I, S2R, S2I, NZ, ASCLE, ALIM,
     +   IUF)
C***BEGIN PROLOGUE  ZS1S2
C***SUBSIDIARY
C***PURPOSE  Subsidiary to ZAIRY and ZBESK
C***LIBRARY   SLATEC
C***TYPE      ALL (CS1S2-A, ZS1S2-A)
C***AUTHOR  Amos, D. E., (SNL)
C***DESCRIPTION
C
C     ZS1S2 TESTS FOR A POSSIBLE UNDERFLOW RESULTING FROM THE
C     ADDITION OF THE I AND K FUNCTIONS IN THE ANALYTIC CON-
C     TINUATION FORMULA WHERE S1=K FUNCTION AND S2=I FUNCTION.
C     ON KODE=1 THE I AND K FUNCTIONS ARE DIFFERENT ORDERS OF
C     MAGNITUDE, BUT FOR KODE=2 THEY CAN BE OF THE SAME ORDER
C     OF MAGNITUDE AND THE MAXIMUM MUST BE AT LEAST ONE
C     PRECISION ABOVE THE UNDERFLOW LIMIT.
C
C***SEE ALSO  ZAIRY, ZBESK
C***ROUTINES CALLED  ZABS, ZEXP, ZLOG
C***REVISION HISTORY  (YYMMDD)
C   830501  DATE WRITTEN
C   910415  Prologue converted to Version 4.0 format.  (BAB)
C   930122  Added ZEXP and ZLOG to EXTERNAL statement.  (RWC)
C***END PROLOGUE  ZS1S2