Spot on thanks Dima! limit(1/x,x=0,dir='+')
returns +infinity Cheers, Vince On 20 August 2013 02:30, Dima Pasechnik <[email protected]> wrote: > On 2013-08-19, Vincent Knight <[email protected]> wrote: > > --001a1133aa8653f2ed04e4510b09 > > Content-Type: text/plain; charset=ISO-8859-1 > > > > Thanks for the answer kcrisman but I'm afraid I'm still not sure I > > understand. > > > > If by 'unsigned infinity' you mean that Sage is returning positive > infinity > > (but assuming that there is no need to return the '+') then I agree but I > > also still don't think that this is the required behaviour right? The > > undirected limit should is not defined (so Sage should return that the > > 'undefined') and given the help file, the output is a bit confusing... If > > I'm missing something please do forgive me :) > > IMHO "unsigned infinity" simply means NaN (Not a Number). > Correct me if I'm wrong here. > > Dima > > > > > Vince > > > > > > On 19 August 2013 19:17, kcrisman <[email protected]> wrote: > > > >> > >> > >> On Monday, August 19, 2013 1:55:04 PM UTC-4, Vince wrote: > >>> > >>> When computing the limit of a function I don't quite seem to be getting > >>> the behaviour that I expected. > >>> > >>> --- > >>> sage: f(x) = 1 / x > >>> sage: print f.limit(x=0) > >>> sage: print f.limit(x=0, dir='minus') > >>> --- > >>> > >>> The first limit returns infinity, but I would expect it to return that > >>> the limit is not defined. > >>> > >> > >> I think we have an unsigned infinity and a signed infinity. It should > >> return the former, from Maxima. > >> > >> > >> > >> > >>> The second (directional) limit confirms this (it returns -infinity). I > >>> was assuming that the default 'direction' for a limit is None and that > a > >>> two directional limit would be computed (which in this case does not > >>> exist). Here's some of the help file that shows why I am perhaps > confused: > >>> > >>> --- > >>> INPUT: > >>> > >>> - ``dir`` - (default: None); dir may have the value > >>> 'plus' (or '+' or 'right') for a limit from above, > >>> 'minus' (or '-' or 'left') for a limit from below, or may be omitted > >>> (implying a two-sided limit is to be computed). > >>> --- > >>> > >>> If anyone could clarify this I'd appreciate it. > >>> > >>> Vince > >>> > >> -- > >> You received this message because you are subscribed to the Google > Groups > >> "sage-support" 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 http://groups.google.com/group/sage-support. > >> For more options, visit https://groups.google.com/groups/opt_out. > >> > > > > > > > > -- > > Dr Vincent Knight > > Cardiff School of Mathematics > > Senghennydd Road, > > Cardiff > > CF24 4AG > > (+44) 29 2087 5548 > > www.vincent-knight.com > > +Vincent Knight > > @drvinceknight > > Skype: drvinceknight > > > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" 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 http://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/groups/opt_out. > -- Dr Vincent Knight Cardiff School of Mathematics Senghennydd Road, Cardiff CF24 4AG (+44) 29 2087 5548 www.vincent-knight.com +Vincent Knight @drvinceknight Skype: drvinceknight -- You received this message because you are subscribed to the Google Groups "sage-support" 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 http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/groups/opt_out.
