On Wed, Jan 19, 2011 at 1:33 AM, kcrisman <kcris...@gmail.com> wrote: > > > On Jan 18, 6:07 pm, Daniel Harris <mail.dhar...@googlemail.com> wrote: >> On Tue, Jan 18, 2011 at 10:51 PM, Robert Bradshaw >> >> >> >> >> >> <rober...@math.washington.edu> wrote: >> > On Tue, Jan 18, 2011 at 2:35 PM, Daniel Harris >> > <mail.dhar...@googlemail.com> wrote: >> >> Hello everybody >> >> >> I am just looking at sketching graphs and I came across a problem that >> >> has me stumped. The graph I am trying to sketch is >> >> >> (x-3) / ( (x+1) * (x-2) ) >> >> >> now I have plotted the graph in sage on my TI-83 and at wolfram and >> >> they all different. Now I am thinking is sage right and the others >> >> wrong? or have I made an error inputting the equation? >> >> >> I would certainly welcome some help on the issue >> >> > What range are you plotting over? -1 < x < 1? -5 < x < 5? This could >> > make a big difference on what the graph looks like. Likewise, what is >> > the scale of the y-axis? I don't think Sage yet tries to remove the >> > asymptotes at -1 and 2 from the plot. >> >> -1.5 < x < 3 the y peak at x=2 is the part that bothers me. It >> doesnt seem to show up on my calc or wolfram alpha? >> > > This is really showing the asymptote. If you do > > > sage: plot((x-3) / ( (x+1) * (x-2) ) ,(x,-1.5,3)) > > sage: plot((x-3) / ( (x+1) * (x-2) ) ,(x,-1.5,3),ymin=-10,ymax=10) > > you'll see what I mean. Unfortunately we don't have any 'guessing' > for the vertical range. That's a bug and a feature at the same > time :) A graphing calculator likely just picks something arbitrary > for that. >
I think I understand now. What was confusing me was when I was looking at a larger scale -30 < x < 30 the peak at x=2 was around 50 but when I kept zoomin in the peak was getting larger, but now I know now that is the asymptote. I guess that is why I need to be able to sketch the graph and not to rely on a computer : ) Thank You both for clarifying the situation Dan > - 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 > -- 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
