On Nov 1, 2008, at 6:28 AM, David Joyner wrote: > > In principle, it's possible to insert a try except clause into the > plot command, > so that it would > > try: > plot(x^2,2,10) > except: > plot(lambda x:real(zeta(x)),2,10) > > There might be more efficient solutions though.
I think this would be bad, but the issue here is that zeta(x) *is* a real number stored as a complex. The issue is sage: RDF(CDF(1)) Traceback (click to the left for traceback) ... TypeError: can't convert complex to float; use abs(z) which is to be consistent with Python complex numbers, but I personally think is a bad idea. > > > On Sat, Nov 1, 2008 at 9:21 AM, [EMAIL PROTECTED] > <[EMAIL PROTECTED]> wrote: >> >> I know about plot?. But you misread my post. I was not trying to >> type Maple commands into Sage. >> >> I was wondering why there should be such a blatant difference >> between plotting x->x^2 and plotting the zeta function on an interval >> on the real axis. My point was that Maple shows this is not >> necessary. >> >> The answer for Sage is that zeta is a numeric function and x^2 is a >> symbolic >> expression. But why do I have to know that if I only want to make a >> simple plot? >> And besides I think the manual of plot does not say anything about >> the >> distinction. >> >> Furthermore zeta is somehow regarded as a complex function and not so >> x^2 (which of course can also be extended to the complex plane). >> Again >> why >> is there a distinction? >> >> I think inconsistency is an enemy of user friendlyness. >> >> Regards, >> Michel >> >> >> >> On Nov 1, 1:24 pm, mabshoff <[EMAIL PROTECTED]> wrote: >>> On Nov 1, 4:59 am, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: >>> >>> Hi, >>> >>> >>> >>>> I want to make a simple plot for a talk. As an experiment I try >>> >>>> plot(x^2,2,10) (*) >>> >>>> and it works as expected. So happily I go for the real thing >>> >>>> plot(zeta(x),2,10) (**) >>> >>>> Unfortunately I get a long list of exceptions but no clear >>>> indication >>>> what the problem is. >>> >>>> plot(zeta,2,10) (*) >>> >>>> yields an empty plot. >>> >>>> plot(real(zeta(x)),2,10) >>> >>>> gives again exceptions..... >>> >>>> After several tries I finally find something that works >>> >>>> plot(lambda x:real(zeta(x)),2,10) (**) >>> >>>> In retrospect I can explain why this magic incantation makes sense. >>>> But I think many users will be baffled by the difference in >>>> complexity between (*) and (**). In Maple there is no difference >>>> between (*) and (**). >>> >>>> This is sage 3.0.5. Released 2008-07-11. >>> >>> Type plot? into a Sage session and you will see plenty of >>> documentation with examples. How is one supposed to know about >>> syntax >>> otherwise? Sage is not a clone of MMA or Maple, so their syntax does >>> not work. >>> >>>> Best regards, >>>> Michel >>> >>> Cheers, >>> >>> Michael >>> >> > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
