CFD Utilities Files

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!
   program extract_functions
!
!  Description:
!
!     EXTRACT_FUNCTIONS extracts the indicated list of functions from a PLOT3D
!  function file, probably to avoid redundant flow interpolation for some other
!  application.  The circumstance that prompted it involves working with volume
!  datasets compatible with BLAYER when only pressure, temperature and electron
!  number density are required for a RADIO_BLACKOUT program.
!
!     The input and output function file names are entered via prompts, and the
!  list of function numbers to extract is entered via a control file.  The form
!  of the input file is determined automatically, and the output file takes the
!  the same form (ASCII or unformatted).  There is no need to deal with the
!  associated grid file.
!
!  Control file ('extract_functions.inp'):
!
!     This should contain a list of integers representing the desired functions
!  and their output order.  The list can take any of the forms handled by the
!  RDLIST utility and it should be on a single line.  Examples:
!
!     2 3 14                    (p, T and electron density from a BLAYER input)
!
!     2 3 15:17                 (p, T and velocity components likewise)
!
!     15-17 1:3                 (any sensible list, not necessarily ascending)
!
!  History:
!
!     03/04/2016  D.A.Saunders  Initial adaptation of earlier utilities.
!     03/05/2016    "     "     Introduced f_io.f90 and made use of it for
!                               much more efficient function file I/O.
!
!  Author:  David Saunders, AMA, Inc./NASA Ames Research Ctr., Moffett Field, CA
!
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