
General
-------
XFOIL and its plot library should compile on any Unix system 
with normal Fortran-77, C, and X-Windows support.  So far,
XFOIL has been tested on the following systems:

  DEC-5000
  Alpha
  SGI
* Sun
* RS/6000
* HP-9000
* Pentium/Linux 

The systems marked with "*" have peculiar features which require slight 
modifications to the Makefiles in the plotlib/ and bin/ directories.  
Examine these Makefiles before building the plot library and XFOIL.

Note that under Unix XFOIL & plotlib run as a single-threaded fortran console 
application with graphics to an X window.  The single thread means that the
program is not set up to respond to events except when it expects mouse input
or clears the graphics window for a new plot.  Window refreshing is not done
as one would do a GUI interface program, normally done by entering an infinite 
event loop and responding to window covering and uncovering with replotting of
the contents.  The best option to use XFOIL under X windows is to enable the 
backing store option to the X server when it is started up.  The backing store
saves window contents and restores them automatically for simple cover/uncover
events. Under Linux the server is usually XFree86 where the backing store is 
enabled in the XF86Config file or as an argument to the startx startup script.


XFOIL can be run under Microsoft Windoze in two ways.  

1) get the Cygwin toolkit (GNU Unix tools ported for Windoze), this includes
   both gcc and g77 compilers which are sufficient to compile XFOIL.
   You also need the XFree86 Version 4.1+ port to Windoze to provide an X
   server or you can use the XFree86 development libraries and use a
   commercial X server (such as eXCEED or X-Win32 or similar).  This is 
   probably appealing to Unix heads compelled to work under the limited 
   toolset under Windoze.  (If you don't think so how would you re-arrange
   huge tables of input data with a single command line?  This type of work
   is nearly trivial under Unix and mind-numbingly tedious using Excel or a
   Windoze text editor.)  Get the Cygwin toolkit even if you use the native
   Win32 XFOIL described below, it gives many of the advantages of running 
   under Unix while still running Windoze!

2) XFOIL and the plot library can be compiled to run natively on
   the Win32 API on Windows NT, 2000, XP using a C plot interface to Win32.

   The Win32 port requires a native Windoze C compiler and Fortran compiler. 
   This source was compiled using Visual C++ and either the Compaq Digitial
   Visual Fortran or the Intel Fortran compiler (Ver 5.0+).  See the README 
   files for further information and Makefile.NT files.

   The Win32 port works but does not yet fit comfortably into a Windoze 
   environment.  Hardcopy support is currently the same as for Unix, as 
   postscript plots.  These can be viewed and converted to more Windoze
   oriented graphics or printed with Ghostview and Ghostscript which are 
   freely available and work well under Windoze.  Win32 native printing
   is one of the next goals for the C interface for the plotlib.  The 
   other gotcha for Win32 XFOIL is the console interface orientation, 
   this can be obliquely construed as an advantage for running XFOIL from
   script input files but when running interactively it would be helpful
   to use Win32 file selection utilities to specify input and output files.


Build sequence
--------------

To install, first build the plot library in  ./plotlib  ...

 % cd plotlib
 % make          (creates libPlt.a)


Then build the programs in  ./bin  ...

 % make xfoil
 % make pplot
 % make pxplot


Documentation
-------------
User Guide is in the  xfoil.doc  file.  If impatient, you can just
run XFOIL in the runs/ directory, which contains a few input files:

 % cd runs
 % ../bin/xfoil

The file  session.txt  contains keyboard inputs for a typical interactive 
session.  If one is lost when running XFOIL, typing a "?" at any command 
prompt, e.g.  

 .GDES  c>  ?  

will always produce a keyboard command menu.

