The software package \MCX is a tool for carrying out highly complex 
Monte Carlo ray-tracing simulations of X-ray beamlines to high precision. 
The simulations can compute all aspects of the
performance of instruments and can thus be used to optimize the use of
existing equipment, design new instrumentation, and carry out virtual
experiments for e.g. training, experimental planning or data analysis. 
McXtrace is based is based on a unique design, inhereted from its sister McStas, 
where an automatic compilation process
translates high-level textual instrument descriptions into efficient
ANSI-C code. This design makes it simple to set up typical simulations
and also gives essentially unlimited freedom to handle more unusual
cases.
