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414 3. Reference Manual
Clusterbound
Usually, CancelTerms deletes several terms at once before performing a numerical error calculation.
The computation of suitable term clusters for this is done automatically by CancelTerms. If the
precasted influence of a term exceeds a given threshold, calculation of clusters is stopped and
cancellation is done term by term. This threshold value is specified by the option Clusterbound.
The following values are allowed:
integer
−Infinity
Infinity
stop calculation of clusters if the logarithm (to base ) of
the precasted term influence is bigger than integer
do not cancel terms in clusters
always cancel terms in clusters
Values for the Clusterbound option.
The default setting is Clusterbound −> −1. Note that deletion of terms using clusters speeds up the
computation significantly.
Errorbound
If the computed error exceeds the given error bound maxerrors, then the term or terms are reinserted.
The option Errorbound specifies the number of successive re-insertions before the algorithm
terminates. Use Errorbound −> Infinity to check all terms for cancellation. The default setting is
Errorbound −> 3.
Level
By default, CancelTerms removes terms from top-level sums (level 0). It is also possible to simplify
sums in deeper levels, i.e. sums occuring inside of expressions. The option Level determines which
level is affected by the simplification. Possible values are:
Level specifications for CancelTerms.
n apply cancellation in level n
{n , n , † † † } apply cancellation in levels n , n ,
All apply cancellation in all levels, starting on top level
If given explicitly, level specifications have to be non-negative integers.
Level −> 0.
The default setting is