Recent content by mrentropy

Thanks for the help. I do remember the discussion in MTW* re Regge calculus and it does seem apropos as I recall, so thanks for the reminder - I'll check it out. Regards, Peter *Misner, Thorne & Wheeler

Well, yes and no. I mean after all if that were completely true, then *nobody* would need exterior calculus, right? The beauty of differential forms (to me anyway) is that things like Stokes's and Gauss's law just "pop out". In practical numerical terms, this means that if you want to...

Oh yes and g_{\alpha \beta} is the metric, but you knew that. Maybe a simpler example to start is this: The Euler equation (setting the density \rho equal to 1) can be written: \partial_t {\vec v} + {\vec v} \cdot \nabla {\vec v} = - \nabla P Nevermind how you solve for P at the...

You're right, and I'll definitely do that. OK so the reason for all of this is in a nutshell is that I'm trying to figure out if it's worth learning exterior calculus, specifically for doing numerical simulations (discrete exterior calculus, aka DEC), for fluid dynamics simulations. I haven't...

Sure: the Navier-Stokes equations, starting with writing out explicitly the viscous stress tensor in a Newtonian fluid. Actually what I'd really like is compressible N-S with MHD, but I think if I see straight up NS I could figure out how to do the rest. :) I just stepped in the door so...

Hi all, Quick question I haven't been able to find the answer to anywhere: Can I use exterior calculus for symmetric tensors? I'm familiar with the exterior calculus approach to things like Stokes's theorem and Gauss's law, but that's vector stuff. It seems to me the only tensors in...

Knowing the gradient of a tensor in cylindrical or spherical coordinates is extremely useful. Are you still in need of the answer? I have had to work it in both systems, both using physical components and using covariant/contravariant index notation. I can search my notes to find it if anybody...

Thanks. I love Perl and I like Larry Wall's statement about easy things being easy and hard things being possible. Of course you always have to match the tool to the job, so the question is: Regarding Fortran modules: What are the the easy things that are made easy by modules, that are...

Fortran90 vs C vs C++: not a troll! Ahhh, yes, the perennial debate that leads inevitably to broken bottles and fisticuffs. I'm being quite sincere here, though, although I'm sure the end of the thread may be ignoble. What I'm wondering is this: --->> What are the ADVANTAGES of Fortran90/95...