>From: Unidata Support <address@hidden> >Organization: UCAR/Unidata >Keywords: McIDAS-X v2002 Linux GMS IMGCOPY Robert, Well, I found out why displaying a GMS image specifying a LAT,LON point for a load: IMGDISP MYDATA/IMAGES.1234 LATLON=-23 -134 and drawing a MAP on top of it will fail MAP SAT under RedHat 7.1 Linux. The problem is actually in the version of g77 shipped with RH 7.1. In that version, the code used for the ICHAR Fortran intrinsic will return negative values byte values where the most significant bit of the byte is set. This goes against the ANSI standard (just looked it up), so it is incorrect. I went to www.groups.google.com and did a search using 'g77 ichar' and found the following comment from a g77 maintainer: From: Toon Moene (address@hidden) Subject: Re: ICHAR on g77 Newsgroups: comp.lang.fortran Date: 2002-04-24 13:22:29 PST [ ichar(char(255)) returns 255 on RH 6.2 and -1 on RH 7.1 ] Richard Maine wrote: > However, I will note that it wasn't too long ago that I noted > the uncertainty about whether ichar could return values larger > that 127 as one of the many "issues" involved in trying to use > characters as substitutes for unsigned integers. (It was in > the middle of a rant of mine suggesting that signed integers > were a more reliable way than character to approximate unsigned > integers). I didn't actually know of this particular case at > the time, but that won't stop me from pointing out that it > supports my previous rant. While true, I still felt that the original behaviour was more "obvious", so I fixed this problem for GCC-3.0. -- Toon Moene - mailto:address@hidden - phoneto: +31 346 214290 Saturnushof 14, 3738 XG Maartensdijk, The Netherlands Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction) Toon Moene's comment indicates that the ICHAR behavior should be correct in GCC 3.0. I took a look at the version of g77 that I use on my Solaris SPARC 2.6 box and get: %g77 -v g77 version 2.95.3 20010315 (release) (from FSF-g77 version 0.5.25 20010315 (release)) Driving: g77 -v -c -xf77-version /dev/null -xnone Reading specs from /opt/gnu/gcc2/lib/gcc-lib/sparc-sun-solaris2.6/2.95.3/specs gcc version 2.95.3 20010315 (release) ... The same listing on the RedHat 7.1 system that I have been using gives: % g77 -v g77 version 2.96 20000731 (Red Hat Linux 7.1 2.96-85) (from FSF-g77 version 0.5.26 20000731 (Red Hat Linux 7.1 2.96-85)) Driving: g77 -v -c -xf77-version /dev/null -xnone Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/2.96/specs gcc version 2.96 20000731 (Red Hat Linux 7.1 2.96-85) It is "interesting" that the version number on Linux is higher than that on Solaris SPARC, but the date on the FSF release is earlier!? I don't know what to make of this at all!! Anyway, what I did to work around this problem was to create a routine called JCHAR and use it in the GMS navigation routine (gms5_nav.for) instead of ICHAR. I relinked all McIDAS applications using the new version of gms5_nav.o and ran tests. IMGDISP of the GMS image and MAPping on top of that image now work correctly. What doesn't work correctly, however, is the drawing of a MAP on top of the same image if it was loaded by DF. The DF load works fine, but the MAP goes into an infinite loop!? Also, the LAT,LON tracking in the MCGUI doesn't work for the image when loaded by DF, but it does work for the image loaded with IMGDISP. Weird, but not something that I am going to worry about much since DF is archaic. The last comment I can make is that the original gms5_nav.for when turned into C by f2c and then compiled by gcc works with no problems. This says that the problem is isolated to g77, but I havn't figured out why the same code has problems on Compaq True64. Sigh... Anyway, I will be playing with this some more and then adding the mods for gms5_nav.for to a new addendum at some point in the future. If you feel like you need the modified code now, I will stick it out on our FTP server for you to grab. Ciao, Tom >From address@hidden Wed Aug 14 15:32:33 2002 Strangely enough..gcc 2.96 was known to have problems, it was not an "official release", which as it turns out was one of the reason several people around here don't like RedHat. I will probably leave well enough alone for now since my machines are working okay. I do have one RH 7.1 box that I set up for testing, but will just use the 2.95 or 3.0 compilers. Thanks, Robert >From address@hidden Thu Aug 15 09:39:09 2002 >Subject: Re:20020814: McIDAS-X v2002 MAP errors on GMS image IMGCOPYed to >SPARC (cont.) I will wait for the next addendum I believe since it works okay on the systems we have. I have another question for you on the GINI radar composites which I will send in a separate message. Thanks, Robert
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.