WHATS NEW IN VERSION: 
  0.0.5: Minor bug fixes. Related to the use of the code as a python module. 
  Now also handles scalar input that is outside grid range. 
  For scalar input, output is also scalar.

  0.0.4: To be able to handle `out of grid range' input values; the default
  here is to use nearest grid point.  
  Now program works for input files with only one line (star). 
  Added function get_mass_radius() . 
  When run in script mode, the text output files now include radius along with mass. 
  Now [Fe/H] is allowed as input instead of Log(Z) in text input file.
  A flag 'isfeh', which can be True or False, is introduced in the functions get_mass_radius() 
  and get_dnu_numax().   
  Finer grid spacing in age during the He core burning phase.  

  0.0.3:
  Changes in the following files: asfgid.py and interp_grid2.ebf. 
  Version 0.0.1 had a bug in line 165 of asfgrid.py, which could result in wrong answers.
  Also, the file interp_grid2.ebf, was of lower resolution than 
  required to get reliable answers.


DESCRIPTION:
asfgrid 0.0.5:  computes (1) corrected delta_nu to be used in delta_nu scaling relation, 
                         (2) correction factor f_delta_nu for delta_nu scaling 
		 	     relation (see Eq 5 in Sharma et al. 2016, ApJ,822,15),
                         (3) mass and radius using delta_nu correction,
                             by interpolation over a grid. 
Copyright (c) 2015 Sanjib Sharma, Dennis Stello
License: AGPL see <http://www.gnu.org/licenses/>

The interpolation grid covers all combinations of the following values of log(Z) and mass
logz=[-4.7212464 , -3.7212464 , -3.12124848, -2.92124602, -2.7212464,
      -2.52124598, -2.32124678, -2.12124618, -1.92124602, -1.7212464,
      -1.52124598, -1.42124622, -1.32124678]
mass=[ 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.94, 0.96,
       0.98, 1.00, 1.10, 1.20, 1.40, 1.60, 1.80, 2.00, 3.00, 4.0]


INSTALLATION:
1) requirements: scipy__version__ >= 0.14.0
2) Data files should be in current directory of the installed code.  
   If you want to put the data files that come with the program in a
   different directory than where the code is installed, you need to 	
   set the appropriate datadir path by editing line 150, which is currently
   self.datadir=''
   
3) You will need the python ebf module to read the grid interpolation files.
   These can be installed by

   For non root do:
   pip install ebfpy --user
   For root do:
   sudo pip install ebfpy 

If required see http://ebfformat.sourceforge.net/
for further details on installation of ebf.


RUNNING THE CODE:
asfgrid.py is the main code. It can be run as (1) a script or as (2) a python module.

(1) ----> For script mode <-------------
To run make sure it is executable by e.g.
chmod 755 asfgrid.py
The input and output is via ascii files 
Check usage with
./asfgrid.py -help 

   USAGE:
   	 asfgrid.py inputfile 
   
   DESCRIPTION:
   	 Output file name is constructed from filename with suffix .out 
   	 Input file should be ascii as follows
   	 evstate logz    teff      dnu     numax
         1      -1.97    4659.8    8.81    92.36
         1      -1.98    4903.2    13.1    157.3
   
   	 First line must contain column names
   	 Column names can be in any order but need to follow names given below
   OPTIONS:
   	 Possible input/outputs are
   	 1) (evstate, logz, teff, dnu, numax)      ->(mass,radius)
   	 2) (evstate, logz, teff, mass, logg)      ->(dnu,numax,fdnu)
   	 3) (evstate, logz, teff, mass, logg, mini)->(dnu,numax,fdnu)
   	 4) (evstate, feh, teff, dnu, numax)       ->(mass,radius)
   	 5) (evstate, feh, teff, mass, logg)       ->(dnu,numax,fdnu)
   	 6) (evstate, feh, teff, mass, logg, mini) ->(dnu,numax,fdnu)
         (1) and (4) are typically used to go from observations to
   	 resulting mass and radius.
         The rest are typically used to go from any stellar model to
   	 predicted dnu (corrected), numax and correction factor.
         If your input is from a model that includes mass loss, where
   	 mass<mini, correct interpolation is assured by using the third or
   	 sixth option. 

   VARIABLES:
         evstate     (array): 1=Pre RGB tip, 2=Post RGB tip
         logz or feh (array): Log(Z) log metallcity or [Fe/H]=log(Z/Z_solar).
                              If input feh, program assumes Z_solar=0.019
                              to convert to LogZ in the grid.
         teff        (array): Effective temperature.
         mass        (array): Actual mass; when written as output, it is the
                              mass obtained using the dnu-scaling relation
                              corrected with fdnu. 
         radius      (array): Radius; corresponds to the radius obtained using
                              the dnu-scaling relation corrected with fdnu. 
         mini        (array): Initial mass. Useful for cases with mass loss,
                              where actual mass is <= mini.     
         logg        (array): Log(gravity).
         dnu         (array): Observed large frequency separation (micro Hz);
                              when written as output, it corresponds to the
                              radial mode frequency-based dnu from the grid. 
         numax       (array): Observed frequency of max power (micro Hz);
                              when written as output, it corresponds to the
                              scaling-based numax from the grid. 
         fdnu        (array): Correction factor for dnu scaling relation.

Run examples (using the three test input files provided): 
./asfgrid.py test1.txt 
./asfgrid.py test2.txt 
./asfgrid.py test3.txt 


(2) ----> For module mode <------------
python or ipython to start python. Then
>>> import asfgrid
>>> help(asfgrid)

Run example: 
>>> import asfgrid
>>> evstate=[1,1]
>>> logz=[-1.97,-1.98]
>>> teff=[4659.8,4903.2]
>>> dnu=[8.81,13.1]
>>> numax=[92.36,157.3]
>>> s=asfgrid.Seism()
>>> mass,radius=s.get_mass_radius(evstate,logz,teff,dnu,numax)
>>> print mass,radius
>>> logg=s.mr2logg(mass,radius)
>>> dnu,numax,fdnu=s.get_dnu_numax(evstate,logz,teff,mass,mass,logg)
>>> print dnu,numax


DATA FILES:
dnu_grid_evstate.txt  Raw stellar grid (MESA) in ascii (not used by asfgrid)
dnu_grid_evstate.ebf  Raw stellar grid in ebf format (not used by asfgrid)
Column description:

  evstate:    Evolution state (in this file evstate has more states then used in the code)
               -1=PreZAMS 
                0=MS 
                1=Subgiant+RGB 
                2=Stable HeCoreBurn 
                3=AGB 
               -2=between 1 and 2  
  mass        Stellar mass (M_Sun). Since the grid has no mass loss this is the same as mini
  z           Metallicity 
  lum         Luminosity  (L_Sun)
  teff        Effecive temperature (K)
  sradius     Stellar radius (R_Sun)
  age         Age (Gyr)
  model       Consecutive model number 
  numax       Numax (micro Hz) from the scaling relation using mass, radius,
              teff assuming numax_Sun=3090 micro Hz 
  dnu_int     Delta_nu (micro Hz) from sound-speed integral 
  dnu_sc      Delta_nu (micro Hz) from the scaling relation using mass, radius,
              teff assuming numax_Sun=135.1 micro Hz 
  dnu_frq     Delta_nu (micro Hz) from fit to radial mode frequencies 
  dp          Period spacing (s) from buoyancy integral.
  central_he4 Central fraction of He4
  logg        Log of gravity 


grid_interp1.ebf      Stellar grid in format for asfgrid to interpolate in (evstate, logz, teff, mass, logg_teff)
grid_interp2.ebf      Stellar grid in format for asfgrid to interpolate in (evstate, logz, teff, mass_nu, logg_teff)
Column description:
  As above plus:

  logg_teff   A function of logg and log(teff), which is almost monotonic with age. 
               For logg<<4.2,  logg_teff ~ log(teff). 
  mass_nu     Mass computed from dnu-scaling relation using logg, dnu and teff