  Modern investigations of magnetic chemically peculiar stars reveal a variety
of complex processes in their atmospheres. Realistic spectrum synthesis
modelling of these objects has to take into account anomalous chemical
composition, strong magnetic field and chemical stratification. These effects
complicate calculation of theoretical spectra, especially when one has to deal
with large number of lines and wide spectral regions. To overcome the
formidable problem of comparing model and observed spectra for magnetic
chemically peculiar stars, a new suite of spectrum synthesis programs was
developed. Here we describe in detail the synthesis codes, Synth3 and Synthmag
and present examples of their application to various aspects of the
peculiar-star surface phenomena. The new codes proved to be reliable tools for
the line identification, magnetic field determination, chemical abundance and
stratification analysis.
