PTC_TWISS Example6 6D ptc_twiss for LHC lattice

Run command:
../madxp < lhc.madx [> lhc.out]

with the Mad-X output directed to the terminal or to 
the "*.out" file.

In this example, the PTC_TWISS command is applied to calculate 
the Ripken-style 6D parameters.

Input:
******

Lattice: the usual LHC input files
Control: lhc.madx

Output:
*******

twiss_lhc:      6D PTC_TWISS output
end.map:        Matrix at end
normal_results: First order chromaticity
fort.18:        Debug map till second order