On 2 March 2016 at 14:58, Robert Helling <[email protected]> wrote: > Hi, > > On 29.02.2016, at 17:10, Linus Torvalds <[email protected]> > wrote: > > Of course, I didn't actually check that the fancy math gives mostly the same > results for air, but I assume Robert did. > > > > this is what I spent some time on. As I said, the van der Waals equation > (which is what one learns in undergrad physics to be relevant to real gases) > turns out to be terrible in this respect, the equation I used is better. But > still, it is not perfect when compared to the empirical values from > Wikipedia. But maybe this could be expected given that it only comes with > two parameters (the critical temperature and the critical density). > > Have a look yourself: > >
hmm, that looks quite off to me considering the scale (the level of precision) of the ordinate. > > The blue dots are the table from Wikipedia, the yellow curve is van der > Waals and the red is the one from my patch. There is a clear trend to be too > small but I would rate this as „good enough“, in particular as it also > generalizes to other gases. > so, those least-square polynomials that i posted went exactly through the points and are still the most accurate solution in this thread (if the empirical values make sense), but i guess they won't cover all use cases. lubomir -- _______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
