Overview

Python uses a keyword based parameter file the specify a model. A portion of a parameter file (which must have the extension .pf) is as follows:

Wind.radiation(yes,no)                          yes
Wind.number_of_components                  1
Wind.type(SV,star,hydro,corona,kwd,homologous,yso,shell,imported)                   sv
Wind.coord_system(spherical,cylindrical,polar,cyl_var)          cylindrical
Wind.dim.in.x_or_r.direction               30
Wind.dim.in.z_or_theta.direction           30

Each line begins with a keyword followed optionally by a comment in parentheses, and then a value, e.g

• Keyword: Wind.type

• Comment: SV,star,hydro,corona,kwd,homologous,shell,imported

• Value: SV

The comment generally specifies a set of valid choices or the units in which information is expected.

When a series of choices is presented, one does not need to enter the complete word, just enough to provide unique match to the choice.

One does not need to create a parameter file before running Python. Instead, assuming one is not working from a template parameter file, one simply invokes Python.

py my_new_model

or

py -i my_new_model

Python then queries the user for answers to a series of question, creating in the process a pf file, my_new_model.pf, that can be edited and used in future runs.

An example of a line presented to the user in interactive mode is:

Disk.mdot(msol/yr) (1e-08) :

There the number in the second set of parenthesis is a suggested value of the parameter. The user types in a new value and a carriage return, or, if the the suggested value seems appropriate, responds with a carriage return, in which case the suggested value will be used.

The -i switch above indicates that Python should accumulate all of the necessary inputs, write out the parameter file, and exit, which is useful if one is not completely sure what one wants.

Changes in the input files as the code evolves

Occassionally, new input variables will be introduced into Python. In this case, when one tries to run a parameter file created with a previous version of Python in single processor mode, the program will query the user for the parameters that are missing, and then attempt to run the program as normal.

If the original name of the parameter file was test.pf, the modified version of the parameter file will be written to test.out.pf, so one normally copies, in this case test.out.pf to test.pf to avoid having the reenter the variable by hand if one wishes to run the parameter file a second time.

A better approach, if one is aware a change to the inputs has been made, is to run the old parameter file with -i switch, copy the test.out.pf to test.pf, and then run the program normally.

Alternatively, if one heeds to modify a number of input files, once one knows what the change is, one can simply edit the .pf files directly.

(In multiprocessor mode, if the inputs have changed, the program will fail at the outset, requiring one to got through the process of runnning the program with the -i switch, copying the test.out.pf to test.pf, and then running normally.)