DM2003 has powerful graphic engine that can display not only "raw" numeric data, but also arbitrary functions on the given data calculated dynamically without actual data changes. Series may be in either data or functional mode. Data series must be associated with worksheet and display numbers from worksheet (possibly transformed by expressions). Functional (or parameterized) series don't use numeric data; instead, point coordinates are defined as a result of evaluation of X and Y expressions, both depend on cx parameter whose values belong linear grid ranged from cxmin to cxmax and divided into given number of equal intervals. See expression syntax for more details about available functions and operators. Notice that it is possible to enable a cache associated with every series so that point coordinate calculations will not affect plotting performance.
Why use expressions?
Example: in many cases the electrical conductivity of semiconductors obeys so-called "activation law": R~exp(Ea/kT). You can easily linearize R(T) dependence and determine activation energy Ea if you plot ln(R) vs. 1/T: set Y expression to "ln(cy)" (or just select logarithmic Y axis tick layout) and X expression to "1/cx", then use Ruler tool to determine curve slope. In many cases such "on-fly" plot transformations is much more convenient than direct data recalculation, and allows you easily make experiments with your data. Manual Fitter tool available in the Fitting menu also can help you to find parameterized expressions.
Series Properties dialog box should be used to change various parameters of the selected series, grouped on two tabs - Data and View:
Data - based or Parametric radio buttons determine series type. For data - based series, you should define data range (first line, last line and associated worksheet). If worksheet is not selected, or first line is greater than last line, or equal to -1, series is treated as empty and will not be displayed. For functional series, define parameter range and number of points. Also you may set interleave factor to make plotting faster if the number of points is more than several thousands.
X/Y Axis coordinates - select column, error bar column (only for data - based series) and expression (required for parametric series).
Show points - check this flag and define point attributes if you want to display points on the plot curve.
Show lines - check this flag and define line properties if you want to connect curve points with lines. If you uncheck both flags the series will be not empty, but invisible. For your convenience, there's preview image at this tab.
Caption - like column caption, the plot series can have associated text string that should be used as a description.
X/Y Axis - select which pair of plot axes should be used to define coordinate plane. Notice: in DM2003, any plot actually have four independent coordinate planes, and each series associated with its own coordinate system! Keep in mind that when you select (or make current) another series with different set of associated axes, real coordinates implicitly change as well.
Visible checkbox - determines whether this series should be displayed.
Marker - as of build #325, marker ("leader") position may be changed, so it can be used to select points.
Area border - select an object from this list to display filled area limited by series curve and the border of selected object. Any non-empty series or axis or plot label (only arrows and lines) may be selected.
In addition, you can change various visual attributes of the series such as colors, point size and shape, line width etc. Warning! if you set line width greater than 1, display output may seriously slow down and even result in the crash of video driver if the number of lines is greater than several thousands. Although with 1px solid line DM2003 can easily display as much as a million of lines (and this is the fastest mode since only one PolyLine() GDI call is made!), using line styles and thick lines require so called "geometric" pens which are many times slower. On Win9.x, it is just impossible to apply a style on the thick lines, and the number of points in PolyLine() is also limited to several thousands (this is a limitation of its 16-bit GDI core).