On 10 March 2016 at 02:40, Linus Torvalds <[email protected]> wrote: > > > > On Wed, Mar 9, 2016 at 4:20 PM, Linus Torvalds > <[email protected]> wrote: >> >> and the plot doesn't look that far off what we have now. > > > To verify that, I just plotted our old helium curve on top of the same plot: > > > there *are* actually two lines there if you look closely, although it really > just looks like the line gets a bit fatter up at roughly 550 bar. > > So I think my R math is correct >
that's certainly an alternative to the linear mixing of the two polynomials. in terms of which one is the better fit i have one observation. if add the data from bauer.com for helium (which pretty much looks to be for a higher T than 300K) and plot @ google: 1.0 + 4.87320026468e-04*x - 8.83632921053e-08*x^2 + 5.33304543646e-11*x^3, 1.0 + 0.0004796109868797936*x - 0.00000004077670019935*x^2 + 0.00000000000077707035*x^3, 0.9998885418429937 + 0.0005435539837400252*x - 2.3960530861159e-7*x^2 + 1.999279624e-10*x^3 + 6.760135e-14*x^4 ^ 1) LS fit from the data of both temperatures, 2) linear mix of the two individual polynomials, 3) the bauer.com polynomial i observe a tendency for Z to rise more with the upper pressures (we need to look in the < 300bar range, due to the bauer.com cap), and that remains true for the linear mix of polynomials, while with the LS fit of the two temperatures there seems to be a less steeper rise for Z at higher pressures. i'm pretty sure that i can think of a data set that will render both methods non-optimal, so i wonder which one is the better fit in the 1-500bar case. we can't really be sure unless we have the actual experimental data @ 300K. it's probably a good idea to update the .C file coefficients, so that any viewers can trace them back to the .R file which holds "the proof", essentially. lubomir -- _______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
