As far as I know Les, the 2.3.3 does exist, but not under RH, Centos or the "big 3" for that matter. I recall seeing a few rpm pkgs for some distros I've never heard of. As for it being exactly what is needed, I can't say anything for sure, other than what the runtime error prints out. I've looked in the librt.so.1, and it does in fact have an external call to 2.3.3, but beyond that, I dunno. It could well be a compiler error too. Many of the folks who have had success building and running WRF are doing so under an earlier version of the PG compiler, I think pre-6.0. Since I don't own the portland group compiler, just using the trial version, I'm not entitled to any support from them, and as I stated earlier, there has been little to no discussion about late date versions of Linux. The other thing that is secondary to the WRF build is some fortran utilities and one shared object file that will not build under the x86-64 due to some relocation issues. I think all the code that I'm attempting to build/run was pretty well tested out on the i386 versions of several OS', but primarily RH3. On another note, I do have folks that have sent me some configuration files for the MM5 model running under the x86-64 RH distro, and they all say it really kicks ass compared to the 32-bit builds, but that is again, using an earlier version of the Intel compiler and earlier code to boot. I'm not one to stay on the bleeding edge of things, but I figured there would not be too much change from 3 to 4, but I'm finding out different. As for the actual 2.3.3 library, I don't know if it will be in the 3.5 distro of Centos or not, but its worth a try. Les Mikesell wrote: > >There is an x86_64 version of Centos3.5. But, I think both >will have gcc-3.2.3 which should be the libraries that match >compat-glibc on 4.x. Are you sure you need exactly 2.3.3? > > > -- Snowman