CFD Utilities Files

EXTRACT_COLUMNS Description:

PURPOSE:

   Extract specified columns from a text file consisting of multiple
   columns of floating point numbers, possibly needed scaling and/or
   shifting.  The scaling is of the form x' <- scale * x + shift.

   Enhancement:  This version performs the following transformation:

      x' <- scale * (x ** power) + shift   where power is usually 1.

   This version handles embedded text lines or lines with fewer than
   the specified number of columns (possibly header lines of integers)
   by either transmitting them intact or suppressing them as requested.

   Converting to absolute values is done with a kludge:  use a negative
   column number.

SAMPLE CONTROL FILE             ! Control file name: 'extract_columns.inp'
                                ! See footnote below.

   INPUT FILE        OUTPUT FILE
   traj.plt          SHARP-V7.trajectory

   # COLUMNS INPUT   # COLUMNS OUTPUT   TRANSMIT ODD LINES?
   26                4                  T

   COLUMN NUMBERS TO EXTRACT
   1  9  6           25

   POWERS
   1. 1. 1. 1.

   SCALES
   1. 1. 0.020885472 1.

   SHIFTS
   0. 0. 0.          0.

   OUTPUT FORMAT                ! Exactly as for F90, with parens.
   (F5.0, F9.5, 1P, E10.3, E15.7)

HISTORY:

   07/16/01  D.Saunders  Initial implementation for dealing with
                         trajectory results from Traj.
   08/23/01    "   "     Transmit or suppress text lines or lines that
                         generate errors when read as "ncol_out" reals.
   09/27/02    "   "     Mission outputs required 500+ chars/line and
                         ~40 columns input.  Kludged a way of ignoring
                         the output sign via a negative column input.
   09/10/03    "   "     Introduced POWERS to enable conversion of
                         temperatures (F) to heat fluxes (W/cm^2),
                         albeit in two runs of this utility.
FOOTNOTE:

   If extract_columns.inp is not found, the program prompts for the simpler
   option of grabbing any subset of columns in any order (with no option
   for scaling or shifting or reformatting as originally intended).