Re: 1 equals 3 (among others)

*To*: mathgroup at smc.vnet.net*Subject*: [mg32214] Re: 1 equals 3 (among others)*From*: "James Richitt" <james at citicom.com>*Date*: Sun, 6 Jan 2002 03:38:30 -0500 (EST)*References*: <a13v7l$dgb$1@smc.vnet.net> <a162s3$pne$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

If you have problems seeing the full numerical values along the y-axis, you should try the PlotRegion switch... Plot[ f[x], {x, 0, 5}, PlotRegion->{{0.1, 1}, {0.1, 1}}] James "Grischa Stegemann" <Stegemann at physikDONOT.SPAMtu-berlin.de> wrote in message news:a162s3$pne$1 at smc.vnet.net... > On Fri, 4 Jan 2002 10:13:09 +0000 (UTC), Grischa Stegemann wrote: > > > > In[1]:=f[x_] = (4 - x + Sqrt[-4*(3 - x) + (x - 4)^2])/2; > > In[2]:=Simplify[-4*(3 - x) + (x - 4)^2] > > Out[2]=(-2 + x)^2 > > Oh stupid fool I am! All the time I have dealt with complex numbers > but only in this special case everything becomes real. So I have > totally ignored that Sqrt[x^2]=Abs[x]. This of course explains the > numbers I mentioned. > > Nevertheless I found out that this wasn't actually my problem. The > actual problem arised from the plot > Plot[f[x],{x,0,5}] > because I have neglected the numbers at the y-axis and thought that > Mathematica is giving me lots of rubbish. > In this plot you can see numerical noise which can be hidden by > e.g. giving PlotRange->{0,3}) but which doesn't appear if you plot > g[x_]=Sqrt[-4*(3 - x) + (x - 4)^2]; > Plot[g[x],{x,0,5}]. > > OK, this is not really essential... ;-) > > > Thanks to all who pointed me to my stupidity. > > > Bye, Grischa > -- > ------------------------------------------------------------------------- > Grischa Stegemann Technische Universität Berlin -- > >