ADAS Subroutine dnaq

      SUBROUTINE DNAQ(A0,A,B0,B,Q,NMAX,JSWICH)
      IMPLICIT REAL*8(A-H,O-Z)
C-----------------------------------------------------------------------
C      PURPOSE: GIVEN A0 AND ITS FIRST NMAX DERIVATIVES IN ARRAY A,
C      AND GIVEN Q AND NMAX, CALCULATES B0 AND ARRAY B, BEING THE
C      VALUE AND FIRST NMAX DERIVATIVES OF (A0)**Q
C
C      FOR PERHAPS GREATER SPEED, YOU MAY SET JSWICH TO 2 IF Q IS -2.0
C      JSWICH TO 3 IF Q IS -1.0
C      JSWICH TO 4 IF Q IS -0.5
C      JSWICH TO 5 IF Q IS -0.25
C      JSWICH TO 6 IF Q IS 0.25
C      JSWICH TO 7 IF Q IS 0.5
C      JSWICH TO 8 IF Q IS 2.0
C      OTHERWISE SET JSWICH TO 1
C-----------------------------------------------------------------------
C UNIX-IDL PORT:
C
C AUTHOR:  WILLIAM OSBORN (TESSELLA SUPPORT SERVICES PLC)
C
C DATE:    4TH JULY 1996
C
C VERSION: 1.1                          DATE: 04-07-96
C MODIFIED: WILLIAM OSBORN
C               - FIRST VERSION.
C
C VERSION: 1.2                          DATE: 19-12-01
C MODIFIED: Martin O'Mullane
C               - Removed junk from > column 72.
C
C VERSION: 1.3                          DATE: 16-05-07
C MODIFIED: Allan Whiteford
C               - Modified comments as part of subroutine documentation
C                 procedure.
C
C VERSION: 1.4                          DATE: 20-07-07
C MODIFIED: Allan Whiteford
C               - Further modification to comments as part of
C                 subroutine documentation procedure.
C
C-----------------------------------------------------------------------
      INTEGER             JSWICH,      NMAX
      REAL*8              A(20),       A0,          B(20),       B0
      REAL*8              Q