File g Draw new data set
By clicking on
the graph (ctrl-N)
Creates one new empty data set. Every point you click on the graph is added to the data set, until you right-click the mouse. You can also drag the mouse, and the program will draw new data points as you go. Ctrl-z will remove the last drawn data point(s), one at a time. Drawing data sets yourself can be useful for subtracting a background from an existing plot, or for re-creating data from a hardcopy or an image. With this you can draw the background into a new plot, and then subtract it from the original plot using the subtract plot command.
The red plot is a hand-drawn background
If you need to multiply your data set with a sliding scale to compensate for measurement sensitivity (for example