*DECK R9KNUS
      SUBROUTINE R9KNUS (XNU, X, BKNU, BKNU1, ISWTCH)
C***BEGIN PROLOGUE  R9KNUS
C***SUBSIDIARY
C***PURPOSE  Compute Bessel functions EXP(X)*K-SUB-XNU(X) and EXP(X)*
C            K-SUB-XNU+1(X) for 0.0 .LE. XNU .LT. 1.0.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C10B3
C***TYPE      SINGLE PRECISION (R9KNUS-S, D9KNUS-D)
C***KEYWORDS  BESSEL FUNCTION, FNLIB, SPECIAL FUNCTIONS
C***AUTHOR  Fullerton, W., (LANL)
C***DESCRIPTION
C
C Compute Bessel functions EXP(X) * K-sub-XNU (X)  and
C EXP(X) * K-sub-XNU+1 (X) for 0.0 .LE. XNU .LT. 1.0 .
C
C Series for C0K        on the interval  0.          to  2.50000D-01
C                                        with weighted error   1.60E-17
C                                         log weighted error  16.79
C                               significant figures required  15.99
C                                    decimal places required  17.40
C
C Series for ZNU1       on the interval -7.00000D-01 to  0.
C                                        with weighted error   1.43E-17
C                                         log weighted error  16.85
C                               significant figures required  16.08
C                                    decimal places required  17.38
C
C***REFERENCES  (NONE)
C***ROUTINES CALLED  CSEVL, GAMMA, INITS, R1MACH, XERMSG
C***REVISION HISTORY  (YYMMDD)
C   770601  DATE WRITTEN
C   890531  Changed all specific intrinsics to generic.  (WRB)
C   890531  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900315  CALLs to XERROR changed to CALLs to XERMSG.  (THJ)
C   900720  Routine changed from user-callable to subsidiary.  (WRB)
C   900727  Added EXTERNAL statement.  (WRB)
C   920618  Removed space from variable names.  (RWC, WRB)
C***END PROLOGUE  R9KNUS
      DIMENSION ALPHA(15), BETA(15), A(15), C0KCS(16), ZNU1CS(12)
      LOGICAL FIRST
      EXTERNAL GAMMA
      SAVE C0KCS, ZNU1CS, EULER, SQPI2, ALN2, NTC0K, NTZNU1,
     1 XNUSML, XSML, ALNSML, ALNBIG, ALNEPS, FIRST
      DATA C0KCS( 1) /    .0601830572 42626108E0 /
      DATA C0KCS( 2) /   -.1536487143 3017286E0 /
      DATA C0KCS( 3) /   -.0117511760 08210492E0 /
      DATA C0KCS( 4) /   -.0008524878 88919795E0 /
      DATA C0KCS( 5) /   -.0000613298 38767496E0 /
      DATA C0KCS( 6) /   -.0000044052 28124551E0 /
      DATA C0KCS( 7) /   -.0000003163 12467283E0 /
      DATA C0KCS( 8) /   -.0000000227 10719382E0 /
      DATA C0KCS( 9) /   -.0000000016 30564460E0 /
      DATA C0KCS(10) /   -.0000000001 17069392E0 /
      DATA C0KCS(11) /   -.0000000000 08405206E0 /
      DATA C0KCS(12) /   -.0000000000 00603466E0 /
      DATA C0KCS(13) /   -.0000000000 00043326E0 /
      DATA C0KCS(14) /   -.0000000000 00003110E0 /
      DATA C0KCS(15) /   -.0000000000 00000223E0 /
      DATA C0KCS(16) /   -.0000000000 00000016E0 /
      DATA ZNU1CS( 1) /    .2033067569 9419173E0 /
      DATA ZNU1CS( 2) /    .1400779334 1321977E0 /
      DATA ZNU1CS( 3) /    .0079167969 61001613E0 /
      DATA ZNU1CS( 4) /    .0003398011 82532104E0 /
      DATA ZNU1CS( 5) /    .0000117419 75688989E0 /
      DATA ZNU1CS( 6) /    .0000003393 57570612E0 /
      DATA ZNU1CS( 7) /    .0000000084 25941769E0 /
      DATA ZNU1CS( 8) /    .0000000001 83336677E0 /
      DATA ZNU1CS( 9) /    .0000000000 03549698E0 /
      DATA ZNU1CS(10) /    .0000000000 00061903E0 /
      DATA ZNU1CS(11) /    .0000000000 00000981E0 /
      DATA ZNU1CS(12) /    .0000000000 00000014E0 /
      DATA EULER / 0.5772156649 0153286E0 /
      DATA SQPI2 / 1.253314137 3155003E0 /
      DATA ALN2 / 0.693147180 55994531E0 /
      DATA FIRST /.TRUE./