
Create XFOIL under Unix:

  Go to the plotlib directory and make the plotlib before proceeding further.

  Before anything is compiled, the Makefile needs to be changed
  to reflect your compiler and library options.  Note that there
  are sample declarations several architectures in the Makefile, you 
  may need to comment or uncomment options for your machine. 

  Then do the make using 
  % make 

  This places all the .o files in the bin directory and puts executables
  xfoil,pplot and pxplot in the bin directory as well.



Create XFOIL under Windoze:

  Go to the plotlib directory and make the plotlib (for Windoze you make in 
  the plotlib/win32 subdirectory using Makefile.NT).  The plotlib must be
  made before proceeding further.

  You need Visual C and either the Compaq Visual Fortran compiler or the 
  Intel Fortran compiler.  You should check the options in Makefile.NT to 
  ensure that they match your system.  The supplied files match the Intel 
  Fortran compiler.

  Compile and link with command in DOS window: 
  C:\Xfoil\bin: nmake /f Makefile.NT

  This places all the .obj files and executables (xfoil.exe,pplot.exe and 
  pxplot.exe) in the bin directory.

  Alternatively you could load all the files into a Visual Studio project
  and create the library that way.


A note on optimization of XFOIL

Most of the run time in XFOIL (in OPER, viscous mode, running polars) is spent
in the subroutine BLSOLVE (in xsolve.f).  Profiling runs on XFOIL show that 
roughly 2/3 of the time is spent in the viscous solver.  This varies a bit 
with the value of VACCEL (matrix drop tolerance), higher values of VACCEL will
speed up the solution but have the potential for convergence problems as the 
the Newton system is approximated by the remaining matrix terms.  Efforts to 
optimize other parts of XFOIL will yield trivial improvements in speed.






