CPF Predictions: Computation of topocentric elements using FORTRAN programs
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                                 Werner Gurtner
                                  October 2005

The following FORTRAN codes are made available:

- Sample program CPF_PGM

  A sample main program for the computation of topocentric elements from
  CPF predictions for a specific station (coordinates are "hardwired" into
  the code).

  It reads

  - some input parameters (Input- and output filenames, start and end time,
    time interval between elements to be computed, a priori time bias
  - a specific CPF file

  It computes (and stores)

  - azimuth, elevation, range, flight time, point-behind angles

  It calls the subroutines EPHINITU and CPF_INTER

- Subroutine CPF_INTER

  A subroutine computing the topocentric elements for a specific epoch
  and station

  It interpolates the satellite positions (subroutine HERMITE) by taking
  into account the flight time and transforms them into topocentric azimuth,
  elevation, range and flight time.

  The number of tabulated positions to be used by HERMITE is hardwired into
  the code (10).

  It calls the subroutines

  -  HERMITE  (interpolation)
  -  DDREH    (rotation matrices)
  -  DMLMAV   (multiplication of matrix with vector)

- Subroutine HERMITE

  A subroutine to interpolate tabulated values by a polynomial for a given
  argument

- Subroutine DDREH

  Computation of a rotation matrix

- Subroutine DMLMAV

  Multiplication of a matrix with a vector

- Subroutine EPHINITU

  Reads a CPF file, keep the values in COMMON /ephihdr/ and /ephi/

- Include files EPHI.INC and EPHIHDR.INC, used by CPF_PGM and ephinitu. EPHI.INC contains the size declaration for the arrays holding all tabulated positions of one CPF file (parameter MAXENT).

The program CPF_PGM has to be linked with all these subroutines.


Author of CPF_PGM, CPF_INTER, HERMITE:

Werner Gurtner
Astronomical Institute
University of Berne

E-Mail: gurtner@aiub.unibe.ch


Author of ephinitu:

Randall L. Ricklefs
Center for Space Research
University of Texas

E-Mail: ricklefs@csr.utexas.edu