From: Dr. Ing. Dieter Jurzitza <dieter.jurzitza@t...>  20111003 09:38:38

Dear listmembers, I have a function (polar diagram) covering many decades of values. I would like to have a constant number of values per decade rather than one with constant spacing (configured via "set samples VALUE") I helped myself by creating a file "sourcefile" containing a correspondingly configured set of values and using those for my plot. I. e. I have two functions RE(x) and IM(x), and rather than performing a set parametric set trange [0.01:1000000] plot RE(t),IM(t) I did a plot "sourcefile" using RE($1):IM($1) where "sourcefile" contains a set of values like 0.01,0.02 ...0.1,0.2, say 10 per decade. This works fine for me but seems somewhat much effort. Is there a more "intelligent" way to tell gnuplot to use I. e. a constant number of values per decade in parametric mode? Otherwise I have to increase the number of samples (nearly ..) beyond all bounds what increases the computation time drastically. I could not find a corresponding hint neither in "help set samples" nor in "help set parametric" Thank you very much for your efforts, take care Dieter Jurzitza    \ /\_/\   ~x~ /\ / \ / \_/ ^^__ _ / _ ____ / <°°__ \ \_/  /     _ _ _ _ if you really want to see the pictures above  use some font with constant spacing like courier! :)  
From: HansBernhard Bröker <HBB<roeker@t...>  20111003 09:52:25

On 03.10.2011 10:42, Dr. Ing. Dieter Jurzitza wrote: > I have a function (polar diagram) covering many decades of values. I would > like to have a constant number of values per decade rather than one with > constant spacing (configured via "set samples VALUE") So what you're trying to do is, essentially, a logscaled 't' axis. Unfortunately, gnuplot doesn't do that by itself. It accepts the command "set log t", but doesn't do anything with it. But read on. > I. e. I have two functions RE(x) and IM(x), and rather than performing a > > set parametric > set trange [0.01:1000000] > plot RE(t),IM(t) Just transform 't' as you go: set trange [2, 6] plot RE(10.0**t), IM(10.0**t) 
From: Thomas Sefzick <t.sefzick@fz...>  20111003 10:13:52

Dr. Ing. Dieter Jurzitza <dieter.jurzitza <at> tonline.de> writes: > ... > I have a function (polar diagram) covering many decades of values. I would > like to have a constant number of values per decade rather than one with > constant spacing (configured via "set samples VALUE") > ... > set parametric > set trange [0.01:1000000] > plot RE(t),IM(t) > ... you may transfer a linear trange into an exponential one via '10**t': set trange [2:6] set samples 81 plot RE(10**t),IM(10**t) 