Different from floating point computations, interval methods provide rigoro
us enclosures of functions, however the limitation of the methods is the ov
erestimation mostly caused by the lack of information on functional depende
ncy. The first cure to the problem is to use a smaller domain, but when a f
unction is complicated, as it often is for practical problems, the number o
f subdivisions becomes quite large. In case of multidimensional systems, th
e computational expense by simple interval methods increases astronomically
. A new approach, the Taylor model method, models a function by a higher or
der polynomial which keeps the majority of the functional dependency, and a
n interval which contains the small remaining error. The method naturally s
uppresses the dependency problem, and proves particularly effective for the
treatment of complicated multidimensional systems.