Contents of this section
The Data Reduction Package (DRP) is a number of small programs to be
used for single dish spectral line data reduction.
It has an advantage (in the author's mind) over traditional packages
like POPS or CLASS, in that it needs
considerably less system resources.
Each DRP command is a program by itself, which will be run from a
shell or even a graphical user interface (GUI) where the operating system
permits it. Individual commands can be combined into more powerful ones
by using shell scripts, so it is the limitation of the underlying shell
that will set the limits for DRP.
Under UNIX the user has a wide choice of shells (sh, csh, ksh, tcsh)
and they are all very powerful. Each of them provides control
structures like if, while, foreach and arithmetic
statements, as well as local and global variables. DRP inherits all
of these by its very nature, together with all the other niceties,
such as history mechanisms, I/O redirection etc.
During the development of DRP it became clear very soon, that a major
advantage of DRP's modular structure is the ease of adding new
features to it. Often the implementation of a new command is only a
matter of minutes, compared to the long time it needs, only to
recompile and relink the bigger packages, let alone tracking their code down
in order to find the place where to implement the modification.
The UNIX version of DRP is completely written in ANSI C, which
helps portability to other platforms with ANSI compliant C compilers.
So far, DRP has been ported (from the original non-ANSI implementation
at SEST) to UNIX, MS-DOS and AMIGA-OS.
The choice of C as the programming language does in no way exclude
the possibilities to write new commands for DRP in other languages
such as FORTRAN.
There is one consequence of the usage of C, though, which is that
channels of spectra in DRP are numbered from 0 to n-1,
rather than from 1 to n, where n is the number of
channels in the spectrum. This has to be kept in mind when using
commands like data, or when specifying ranges by channel number.
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