Re: High precision numbers and Plot[] ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg13702] Re: High precision numbers and Plot[] ?*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Sat, 15 Aug 1998 04:39:30 -0400*Organization*: University of Western Australia*References*: <6qp3b3$ajn@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

a_kowald wrote: > I try to plot a function where I have to use high precision numbers. > That means to get the correct answer I have to use N[f,50]. I set the > Compiled option of plot to false and tried: > > Plot[N[f,50], {i, start, end}, Compiled -> False] > > However, this doesn't work. The result is the same as: > Plot[f,{i,start,end}] > > Any idea what I'm doing wrong ? The likely problem is that the table of values generated by Plot is at machine precision which overrides the use of N[f,50]. Here is one workaround by way of an example. Compare In[1]:= Plot[LegendreP[50], {x, 0, 1}, PlotRange -> All]; with In[9]:= Plot[LegendreP[50, SetPrecision[x, 30]], {x, 0, 1}, PlotRange -> All, Compiled -> False]; Cheers, Paul ____________________________________________________________________ Paul Abbott Phone: +61-8-9380-2734 Department of Physics Fax: +61-8-9380-1014 The University of Western Australia Nedlands WA 6907 mailto:paul at physics.uwa.edu.au AUSTRALIA http://www.physics.uwa.edu.au/~paul God IS a weakly left-handed dice player ____________________________________________________________________