CFD Utilities Files

File tecplot_io.f90 provides utilities for reading 2- or 3-space structured
multiblock (multizone) grids and associated function data in Tecplot format:

   public :: Tecplot_read       ! Read  an entire structured Tecplot file
   public :: Tecplot_write      ! Write an entire structured Tecplot file

   public :: Tec_header_read    ! Read  Tecplot file header records
   public :: Tec_header_write   ! Write Tecplot file header records
   public :: Tec_block_allocate ! Allocate the array fields for one block
   public :: Tec_block_read     ! Read  one block of a structured file
   public :: Tec_block_write    ! Write one block of a structured file

   public :: clone_header       ! Derive one dataset header from another
   public :: clone_zone         ! Derive one zone (block) from another
   public :: deallocate_header  ! Deallocate any dataset auxiliaries
   public :: deallocate_blocks  ! Deallocate arrays of indicated blocks

A superset of the derived data type employed by xyzq_io.f90 for PLOT3D-type
files is included in tecplot_io.f90 to accommodate zone header information,
along with a file header derived data type.

See also a later module for surface triangulations and other unstructured
surface and volume datasets in Tecplottable format:  triangulation_io

Recent tecplot_io history:

09/30/12    Limiting zone dimensions to 3 digits was short-sighted.  5 is now the limit.
10/01/12    Dinesh needed 70 variables; raised string lengths to be more than enough.

12/21/15    Raised the zone limit from 1000 to 3000.
05/26/21    Raised the header%filename limit from 80 to 160 characters for BODY_POINT_DATA purposes.
05/23/23    DPLR's Postflow has been omitting double quotes for unitless variables.  It should be revised, but a
            workaround has been installed here (call add_delimiters before the relevant call to scan4, along with
            a scan2 call to avoid interpretation of '=' as an unquoted variable name).
11/25/24    Reading of a simple file with nothing but variable names in the header, columns of data, and one zone
            with no zone header was found not to work (although Tecplot had no problem).  Therefore, handle this
            special case by assuming POINT order and a single zone.
11/26/24    The special handling of a single zone with variable names (only) needed grid(1)%nzoneaux = 0.
11/29/24    Belatedly handled the pure columns case (no headers anywhere).
12/01/24    Applications that read the file header and process one block at a time required a rethink of how to
            read files with a missing zone header (for which a single zone of column data has to be assumed).
03/23/25    An ADT search-related change to SURFACE_INTERP_2D found glitches traced to entering ndim in the header
            as opposed to determining ndim here.
04/21/25    The internal "variables_present" needs to be set immediately by the case 'V', not below a possible
            cycle that was skipping it.
04/23/25    Bad zone titles were traced to the fact that they are not set by Tec_header_read.  Letting them be
            set by Tec_block_read should still suffice.  See MERGE_FILES as generalized in April 2025.