How To Select and Modify Data

The XYPLOT Database

The XYPLOT database holds each data set loaded from a file in memory. For the DOS version, the database may hold up to 16,000 (x, y) pairs in memory, partitioned into a maximum of 10 data sets. For the Windows and Linux versions, there is no restriction on the size of an individual data set or on how many data sets may be loaded into the database. Data sets may be Duplicated or Deleted from xyplot's memory database using built-in functions. The DOS version also features built-in pruning and concatenation functions.

A data set consists of (x, y) pairs and additional descriptive text information in a header. Data sets may be either real or complex. In complex data sets y is a complex number with a real and an imaginary part. A plot is usually created automatically for a data set loaded from a file into xyplot's database. However, each dataset in the database does not necessarily have to have an associated plot in the display.

Selecting Data Sets

Data sets are selected for mathematical and other operations by selecting their corresponding plots from a Plot List. This means that a data set in XYPLOT's database must appear as a plot for any operation to be performed upon it. The active plot represents the data set upon which single set operations are performed. The active plot is identified by a box or bracket around its number in the Plot List for DOS and Linux versions. In the Windows version, the Plot List appears as a series of circles with the same colors as the associated plots. The active plot is the filled circle.

Two-set operations are specified by selecting the active plot and the operand plot in the Plot List. The operand plot is identified by parentheses surrounding its plot number in the Plot List for the DOS and Linux versions. In the Windows version, the operand plot is the thick outline circle.

If a previously loaded data set does not appear as a plot, you may use the Include (DOS) or Pick (Windows/Linux) functions from the Plot Menu to make a plot of the data set. Include or Pick may also be used to see a list of data sets stored in the database.