RE: FEFF Output File Headers

["Sven L.M. Schroeder" <slms100@compuserve.com>]

Hi all,

I also think it would be best to introduce a flexible system, by which
the user can choose the formatting of the header lines, e.g., with a new set
of cards in the FEFF.INP (start characters for headerline, end characters
for
headerline, delimiters for data column etc.). Then the old formatting system
could remain the default, while anyone wishing to deviate could choose
so freely.

Apart from that, I strongly second Matt's suggestion to turn FEFF into
a library of functions that can be called from standard programming systems,
such as Visual C or Visual Basic under Windows. We will likely have to write
a Windows-based data acquisition system interface for an XAFS beamline,
probably with Visual Basic, and we will need semi-automated on-line
data evaluation based on FEFF. It would make the development much easier if
we
would not have to call a command line executable every time we need FEFF
functionality under Windows.

--
Sven L.M. Schroeder (mailto:slms100@compuserve.com)

Department of Biology, Chemistry and Pharmacy   -   FU Berlin
Institute for Chemistry  -  Takustr. 3, 14195 Berlin, Germany
TEL: +49-(171)-690 2734             FAX: +49-(40)-7511 006128
http://userpage.chemie.fu-berlin.de/~slms100

-----Original Message-----
From: FEFFDEVEL-owner@u.washington.edu
[mailto:FEFFDEVEL-owner@u.washington.edu]On Behalf Of Matt Newville
Sent: 11 January 2002 17:08
To: FEFF Software Development
Subject: Re: FEFF Output File Headers



Hi All,

In principle, any convention should be OK and a convention does
already exist.  And unless something can be done about updating
previous versions, analysis programs will have to accept the old
format for a long time.  Still, I vote against 'do nothing'.

I find the '@#' convention hard to deal with.  First, it comes at
the end of the comment lines, signaling that all the lines read
so far were comments, even if there were lines of numbers-only
columns seen (as some xmu.dat files do). Second, it means looking
at the end of line instead of the beginning, which can be tricky
when files move between Unix, Windows, and Mac.  I don't know of
any plotting programs (gnuplot, Kaleidagraph, IGOR, SigmaPlot,
Origin, or Excel) that has anything like the '@#' convention.

Putting # (or %, ;, !, ...)  in column 1 of output files should be
easy.  Any program that already uses feff.dat could easily be
modified to ignore column 1, I think.  If the license changes,
I'll donate fortran and C routines that reads these feff.dat
files with or without these characters in column 1.

Having other options to tailor the output files for plotting
program could be nice.  That's more work, but if the i/o were well
isolated it would be easy to add additional output formats.  For
example, some programs (Excel, Kaleidagraph) seem to work best
when a predictable number of lines are 'headers to ignore'.  So
letting the user specify the exact number of comment lines
(including none) would be a nice option, and easy to do, assuming
Feff had well isolated i/o.

Beyond that, Feff should be converted into a library of 'high
level functions' that can be used within customized applications.
This would allow Feff calculations to be done directly by analysis
programs that already have plotting capabilities, or used as parts
of Excel macros, VB script, Perl or Hypercard programs, etc.  In
that scenario, Feff doesn't need fancy i/o and can let the calling
program customize i/o (column labels in French, say), or provide a
simple routine to 'write a regular xmu.dat file'.

Again, my view is that putting '#' or something else in column 1
and simplifying the column labels is worthwhile, but I do not have
a strong preference for which details are adopted.  Whatever the
convention is (including the present), it should be documented,
and routines to read the files should be provided.  More than
that, and Feff should be converted from a a monolithic program
that attempts to satisfy everyone into a library of tools.

--Matt

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