! #########################################################
!
! Copyright C. D. Ott and E. O'Connor, July 2009
!
!
!
! EOS constructed on the basis of the Shen et al. 1998
! relativistic-mean field nuclear EOS table. Electrons (fully
! general, based on TimmesEOS) and Photons added.
! 
! Original Shen EOS table extent:
! 
! Density:  10^5.1 to 10^15.4 g/cm^3
! Temperature: 0.1 to 100 MeV
! Ye: 0.01 to 0.56
! 
! Table extent of current table
! (myshen_test_220r_180t_50y_extT_20090312.h5)
! 
! Density: 10^3 to 10^15.36 g/cm^3
! Temperature: 0.01 to 250 MeV
! Ye: 0.015 to 0.56 MeV
! 
! This bigger table is realized by extending the
! original Shen table in multiple ways in multiple
! directions:
! 
! (a) density: 
! Match of pure ideal gas of Ni56 + electrons/positrons +
! photons at densities below 10^7 g/ccm -- at this density
! pressures, energies and entropies match okayish with the
! values in the Shen table. The compositions (A,Z,xh,xa,xp,xn)
! are kept constant in the low-density region and n and p
! chemical potentials are set to 0. 
! -- ideally, at low densities, a full NSE EOS with nuclear
! reaction network (at low T) should be stiched onto the
! Shen; working on that, but not yet ready.
! 
! (b) temperature (extrapolation): 
! At high density: linear extrapolation of everything in T to lower
! temperatures and higher temperatures. At low densities (below 10^7
! g/ccm), ideal gas of Ni56 + electrons/positrons + photons.
!
!
! Variable         Units             Description
! pointsrho	   dimensionless     number of table points 
! 		   		     in log_10(rho)
! pointstemp	   dimensionless     number of table points 
! 		   		     in log_10(temp)
! pointsye         dimensionless     number of table point in Y_e
! logrho	   log10(rho)	     index variable rho
! logtemp	   log10(MeV)	     index variable temperature
! ye		   number fraction   index variable electron fraction
! Abar             A                 average heavy nucleus A
! Zbar             Z                 average heavy nucleus Z
! Xa               number fraction   alpha particle number frac
! Xh               number fraction   heavy nucleos number frac
! Xn               number fraction   neutron number frac
! Xn		   number fraction   proton number frac
! cs2              cm^2/s^2          speed of sound squared
! dedt             erg/g/K	     C_v
! dpderho	   dyn g/cm^2/erg    dp/deps|rho
! dpdrhoe	   dyn cm^3/cm^2/g   dp/drho|eps
! energy_shift     erg/g	     Energy shift for table storage
! entropy	   k_B/baryon	     specific entropy 
! gamma		   dimensionless     Gamma_1
! logenergy	   log10(erg/g)	     specific internal energy
! logpress	   log10(dyn/cm^2)   pressure
! mu_e		   MeV/baryon	     electron chemical potential
! 		   		     INCLUDING electron rest mass
! mu_p		   MeV/baryon	     proton chemical potential
! mu_n		   MeV/baryon	     neutron chemical potential
! muhat		   MeV/baryon	     mu_n - mu_p
! munu		   MeV/baryon	     mu_e - mun + mu_p
!
!
! * energy shift: 
! 
! In some regions the negative nuclear binding energy
! is larger in magnitude than the thermal/excitation energy. In this
! case the specific internal energy (eps) becomes negative. To allow for
! storage and interpolation of eps in logarithmic fashion, the energy
! is shifted up by an energy shift specified in the variable "energy_shift".
! This energy shift is handled internally in the EOS routines.


