Improvements in MAD in view of LHC design

For the design of the LHC (CERN Large Hadron Collider) it is important to perform extensive checks on long-term stability. Comparison of the MAD (Methodical Accelerator Design) program with specialized tracking programs showed that tracking speed of MAD was insufficient. Time-critical routines have been tuned so as to take advantage of vectorization on both Cray and IBM vector computers. The superconducting magnets used in LHC contain various high-order multipole errors. Definition of field error components has been made easier with a new command. Among other effects the multipole errors introduce strong coupling. In LHC it is removed by a few families of skewed quadrupoles. This design requires matching over the whole ring, and forces MAD to recompute a large number of transfer maps repeatedly.<>