Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
Hi all here is another example which is very funny if you see it the first time a=indgen(10)*1D-7 b=a plot,a,b,psym=1 oplot,[0,10],[0,10] because the coordination system is defined by plot it could be a bug too and not only a question about precisions Any idea what is happen here? Cheers Reimar -- Reimar Bauer Institut fuer Stratosphaerische Chemie (ICG-I) Forschungszentrum Juelich email: R.Bauer@fz-juelich.de ------------------------------------------------------------ ------- a IDL library at ForschungsZentrum Juelich http://www.fz-juelich.de/icg/icg-i/idl_icglib/idl_lib_intro. html ============================================================ =======
In article <pan.2007.01.31.20.17.22.400474@as.arizona.edu>, JD Smith <jdsmith@as.arizona.edu> wrote: > On Wed, 31 Jan 2007 11:30:57 -0700, David Fanning wrote: > >> Where else can people go when they want >> to count angles on the head of a pin? :^) > > I prefer counting them in radians, because !RADEG is single precision > floating point. Thanks for chaffing David, JD. I refrained. ;-) IDL has a built-in double precision value of Pi, so I include DEFSYSV, '!DDTOR', !DPI/180.0D, 1 DEFSYSV, '!DRADEG', 180.0D/!DPI, 1 in my startup.pro. Ken
<meinel@aero.org> wrote in message news:1170356284.063756.259710@a75g2000cwd.googlegroups.com.. . > But in this case, all I did was change the x- and y-style on the plot: > > a=indgen(10)*1D-7 > b=a > plot,a,b,psym=1, xstyle=2, ystyle=3 > > No overplotting of relatively large values here. Why does that give me > a bad plot? what's wrong with this plot?
On Wed, 31 Jan 2007 15:56:50 -0600, Kenneth Bowman wrote: > In article <pan.2007.01.31.20.17.22.400474@as.arizona.edu>, > JD Smith <jdsmith@as.arizona.edu> wrote: > >> On Wed, 31 Jan 2007 11:30:57 -0700, David Fanning wrote: >> >>> Where else can people go when they want >>> to count angles on the head of a pin? :^) >> >> I prefer counting them in radians, because !RADEG is single precision >> floating point. > > Thanks for chaffing David, JD. I refrained. ;-) > > IDL has a built-in double precision value of Pi, so I include > > DEFSYSV, '!DDTOR', !DPI/180.0D, 1 > DEFSYSV, '!DRADEG', 180.0D/!DPI, 1 > > in my startup.pro. Good idea. I'm always starting programs with RADEG=180.D/!DPI, but a SYSVAR is a better idea. Come to think of it, why don't you suggest to ITTVIS to add those? It's a rare coordinate calculation in astronomy that doesn't require double float precision in radians. JD
In article <pan.2007.02.01.19.10.01.382641@as.arizona.edu>, JD Smith <jdsmith@as.arizona.edu> wrote: >> IDL has a built-in double precision value of Pi, so I include >> >> DEFSYSV, '!DDTOR', !DPI/180.0D, 1 >> DEFSYSV, '!DRADEG', 180.0D/!DPI, 1 >> >> in my startup.pro. > > > Good idea. I'm always starting programs with RADEG=180.D/!DPI, but a > SYSVAR is a better idea. Come to think of it, why don't you suggest > to ITTVIS to add those? It's a rare coordinate calculation in > astronomy that doesn't require double float precision in radians. > > JD It hadn't occurred to me because it has been in my startup.pro since I first learned about system variables, which was way before I would have thought of asking RSI (I mean IITVIS) to change (gasp!) IDL. I'll submit a feature request. Additional requests from out there in userland might well improve the probability of success. ;-) Ken