Linux

i have a project in numerical calculus in c language

what unix i get better for this?

Ubuntu is the simplest to set up and run for a full featured development environment, and is windows-esque in its facilities and controls. It can even run with windows as dual boot. If you have windows, you might be satisfied with CygWin, also easy to install. It gives you a LINUX feel on a Windows system, but some things like fork and exec are much slower. Once you get your numerical calculus running, none of that matters, it is just another probably CPU bound process running in the system.

C runs fine on any LINUX/UNIX, and c++ and open source flavors of C#, as well as JAVA, which is more all-together and has fewer variants.

right,..
i am working with slackware,...

i am thinking use gentoo and red hat too,.
do you thin that make me some advantage???
since when my project be extensive i want some facilitie for administrating him,...

Well, while I cannot compare admin sorts of gui across all LINUX, I was impressed how much I could do on Ubuntu with menus and the tools on menus. You want a library, API, tool, you can search for it inside Ubuntu and get it installed and included in checking for and installing updates. I did occasionally need to call an admin for help, but even that seemed to be very easy. Ubuntu is designed to be for end users not servers, and has neophite-friendly GUI for that. I was rarely aware of X!

To the OP:

This conversation started over a week ago. I am not being sarcastic when I say you could have tried quite a few operating systems in that time. Ultimately, we don't know what you're looking for, beyond needing a c compiler (which isn't sufficient to distinguish between alternatives).

I suggest you just you go to distrowatch, see what looks good to you, and have some fun with a few test runs (perhaps in a vm).

You mentioned Gentoo and Red Hat and asked if there's some advantage. Well, if you want to think ahead with regard to future employment, knowledge of Red Hat is much more marketable than Gentoo expertise.

Regards,
Alister

thank you very much Alister,...

depending on your computer (i.e., RAM size, HDD size, CPU speed and number, etc.), you can always install the different os versions on a virtual machine (i.e., vmware player) and keep them for testing ...

you can download the various distributions either through distrowatch as suggested by alister or by googling for the operating system you want to download (i.e., "ubuntu download") ...