On Dec 6, 5:30 pm, William Stein <wst...@gmail.com> wrote: > On Sun, Dec 6, 2009 at 4:51 PM, Michel <vdbe...@gmail.com> wrote: > > Thanks for the reply. But no. The problem is not due to the fact that > > the function has a singularity. Indeed. > > > plot(20*log(abs((1+I*x)^4),10),(x,0,3)) > > > fails with the same error which is incomprehensible to me. > > > On the other hand turning the expression into a lambda function made > > it possible to plot it. Thanks for this practical advice. > > > I wish someone could explain this rationally to me. > > > 20*log(abs((1+I*x)^4),10) > > > seems to be a perfectly fine symbolic expression so IMHO it should be > > possible to plot it. > > This is a bug. There absolutely no reason that plotting should give the error > "float() argument must be a string or a number". > We could give an error about not being able to evaluate the function at > certain > points. However, the above error is not OK. The error in fact is > not in plotting > but in making a fast_float compiled version of the expression: > > sage: s = 20*log(abs((1+I*x)^4),10) > sage: fast_float(s,x) > Traceback (most recent call last): > ... > TypeError: float() argument must be a string or a number > > In fact, SAge *should* be using fast_callable, not fast_float. This > works just fine if you force it manually: > > s = 20*log(abs((1+I*x)^4),10) > plot(fast_callable(s,vars=[x]), (x,0,3)) > [[nice picture as output]] > > Many, many thanks for your bug report. It is bug reports from users > like you that really helps Sage to be a first-rate mathematical > software system. > > We are now tracing this issue at 7614: > > http://trac.sagemath.org/sage_trac/ticket/7614
Thank goodness. I have run into this (and reported it on this list) at least twice before :) - kcrisman -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
