Re: Behaviour of Plot/ListPlot & Export

*To*: mathgroup at smc.vnet.net*Subject*: [mg31750] Re: Behaviour of Plot/ListPlot & Export*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Sat, 1 Dec 2001 02:43:43 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <9u4gb3$loh$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, > > Mathematica 4.1.1.0 on Linux > > If I try > > Plot[Sqrt[Prime[n]/Prime[n + 1]], {n, 1, 100}] > > I get: > > Prime::"intpp": "Positive integer argument expected in \ > \!\(Prime[1.000004125`]\)." > Prime::"intpp": "Positive integer argument expected in \ > \!\(Prime[1.000004125`]\)." > Prime::"intpp": "Positive integer argument expected in \ > Prime[2.0000041250000002`]." > > And a bunch more errors, however if I try > > ListPlot[Table[Sqrt[Prime[n]/Prime[n + 1]], {n, 1, 100}]] > > Then it works fine. Presumably Table[x,{x,1,100}] steps through integers > while Plot does not. This is surprising, I expected the same behaviour of > them. Is this a bug? Is this documented (I did look around)? It is a feature, because Plot[] try to adjust the ploting steps for functions like Sin[1/x]. This adjustment need real numbers and this cause the error. > > I have been doing a lot of work with Export[]ing single cells and animated > Gifs. I find Mathematica on something like > Export["somefile.gif",Table[<big list of graphics>]] will produce the > graphics and then export individual frames to /tmp/m<some number> as PNM > files *incredibly* slowly. It will take 3 minutes per image and they are > not complex images. AFAIK this is a known bug. It will be fixed in the next version ... > > The CPU is not utilised during that time, only in small bursts, wait a few > minutes then do the next. For 100 cell animations this is frustrating. The > process tree has PNM.exe and GIF.exe running but doing nothing. Perhaps > they are timing out on some operation? I could run traces for the truely > interested... > > Once it has exported all the images it appears to then keep them all in > memory before creating the GIF. I recently had a 600 frame animation [I > appreciate this should be in an mpeg, and I did so] where mathematica used > 1 Gigabyte of memory plus 128 meg of swap before the kernel VM killed it > for eating all available resources. I respectfully suggest this > architecture is flawed. I am now using ImageMagick for all of these > operations. :-/ > > Also, Mathematica has a bug that I submitted where it crashes on changing > some prefs which was confirmed. > > As an aside is there a version release > than mine and if so am I able to > obtain it? version 4.1.2 ? Regards Jens