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Using SDDS Files with the mpl Toolkit

SDDS files may be used with mpl Toolkit programs. Of course, the programs still use mpl format as well, which is distinguished by the lack of the ``SDDS n'' line at the top of the file. By default, an mpl program will use columns from a SDDS file in the order defined; that is, the first two defined columns will be the abscissae and ordinates, respectively. If three columns are defined, the third column is taken to be the uncertainties for the ordinates. If four or more columns are defined, the third and fourth columns are taken to be the uncertainties for the abscissae and ordinates, respectively.

In order to allow the user to override this default behavior without requiring a rewrite of every mpl program, a special filename syntax is now understood by the routine that reads mpl data for the mpl programs. Specifically, if a filename of the form
name= x-name+ y-name[+ y-uncertainty-name | + x-uncertainty-name+ y-uncertainty-name]
is seen, the indicated columns from the SDDS file name will be used. If the file named by name does not exist, the mpl programs assume that the = and + symbols are part of the filename (allowed under UNIX), and proceed as usual.