Ronan Lamy wrote: > Le mercredi 23 février 2011 à 09:40 +0545, Chris Smith a écrit : >> Ronan Lamy wrote: >>>> Also while writing it, I've noticed 2 additional problems with >>>> Expr.series: >>>> * The order is off by one. >>>> * Its name is misleading since it doesn't return a series. >> >> Can you give examples? In 2084 I get: >> >> >>> cos(x).series(n=3) >> 1 - x**2/2 + O(x**3) >> >> terms valid up TO n=3 are returned (which is consistent with sympy >> range behavior). > > The conventional definition of the order of the expansion is that it's > the degree of the last term included in the polynomial approximation, > so > one less than the order of the excluded terms. Your example is a > second-order expansion, because it gives a second-order approximation. >
The documentation has been updated to reflect that terms up to O(x**n) are returned. > Our definition might be more convenient, but it's not the usual one. > Maybe this is just a documentation issue. Til now we have lived with terms refering to factors in a Mul and factors refering to terms in an Add...do we need to change the name from series to something else or should we just update the docstring? /c -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
