SAO TDC ASCII Parameters

When a program with numerous parameters, such as skymap, rgsc, or star, is used frequently, it soon becomes desirable to save values between executions of the program. I have designed and implemented a system of subroutines and utilities to make this task easy for both programmers and users. The fastest way to save values is to store the parameters in a Fortran common or C data structure and write the whole structure to disk in one output operation, later retrieving it in one input operation. While this technique is fast, it is not easily extensible when new parameters are added to a program, and the parameter files are not portatble between computers of different architecture. Every subroutine which uses the structure must be recompiled when any change is made. In addition, the binary parameter file cannot easily be read outside the program which uses it.

A simple ASCII parameter file format has been designed based on the FITS image file header, and software has been created to utilize it. skymap uses the IOLIB library which contains subroutines to read from and write to an ASCII parameter string, using only the name of the parameter, a variable to contain the binary value, and a data type flag.

The parameter file structure is clear enough that such a file can be edited by an ASCII file editor such as vi or emacs. Either the command-line features of skymap described below or stand-alone programs can be used to read or modify the parameter files. Values can be changed or checked on the command line, allowing the the Unix shell to be used in a way similar to the IRAF Command Language for batch operation of programs. Although this is a fairly rudimentary system, it has been in use for several years and is fairly well debugged.

Parameter Format
Reading and Writing Parameter Files
Using Parameter Files

Last updated 17 February 1994 by Doug Mink