*     G01RTF Example Program Text
*     Mark 21 Release. NAG Copyright 2004.
*     .. Parameters ..
      INTEGER          NIN, NOUT
      PARAMETER        (NIN=5,NOUT=6)
*     .. Local Scalars ..
      DOUBLE PRECISION X, Y
*     .. External Functions ..
      DOUBLE PRECISION G01RTF
      EXTERNAL         G01RTF
*     .. Executable Statements ..
      WRITE (NOUT,*) 'G01RTF Example Program Results'
*     Skip heading in data file
      READ (NIN,*)
      WRITE (NOUT,*)
      WRITE (NOUT,*) '  X          Y'
      WRITE (NOUT,*)
   20 READ (NIN,*,END=40) X
*
*     Compute the value of the derivative of the Landau density function
*
      Y = G01RTF(X)
*
      WRITE (NOUT,99999) X, Y
      GO TO 20
   40 STOP
*
99999 FORMAT (1X,F4.1,3X,1P,D12.4)
      END