Hello, TLDR: Proposal is to support the precision as argument to ex.series() instead of the order term exponent. Visible changes only expected with Laurent series.
Long version: There are two fundamentally different methods to compute series expansions of symbolic expressions: differentiation (GiNaC, Pynac, SymPy) and, for a subset of expressions, combinations of inverse, reverse, and other tricks applied to ring series (Pari, Flint). Pro/Con: differentiaton: slow but general ring series: fast but can only handle univariate and a subset of functions So it makes sense to speed up the first in case there are only suitable functions involved. However, with ring series a fixed precision is applied which is not the same as the exponent of the order term because series can shift left by division through x (Laurent series) which shifts the order term as well. OTOH the Sage ex.series argument prec defines the final order term (as does SymPy with n, but they don't use ring series yet). To be able to apply both methods with the same interface it seems necessary to not set an order term exponent in the series command but the precision. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
