*DECK PGSF
      FUNCTION PGSF (X, IZ, C, A, BH)
C***BEGIN PROLOGUE  PGSF
C***SUBSIDIARY
C***PURPOSE  Subsidiary to CBLKTR
C***LIBRARY   SLATEC
C***TYPE      SINGLE PRECISION (PGSF-S)
C***AUTHOR  (UNKNOWN)
C***SEE ALSO  CBLKTR
C***ROUTINES CALLED  (NONE)
C***REVISION HISTORY  (YYMMDD)
C   801001  DATE WRITTEN
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900402  Added TYPE section.  (WRB)
C***END PROLOGUE  PGSF
      DIMENSION       A(*)       ,C(*)       ,BH(*)
C***FIRST EXECUTABLE STATEMENT  PGSF
      FSG = 1.
      HSG = 1.
      DO 101 J=1,IZ
         DD = 1./(X-BH(J))
         FSG = FSG*A(J)*DD
         HSG = HSG*C(J)*DD
  101 CONTINUE
      IF (MOD(IZ,2)) 103,102,103
  102 PGSF = 1.-FSG-HSG
      RETURN
  103 PGSF = 1.+FSG+HSG
      RETURN
      END