The SizeXY form () plots a shaped marker whose width and height vary independently acoording to two supplied data coordinates. The marker shape can thus encode two additional dimensions of the plot.
The actual size of the markers depends on the setting of the Auto Scale option. If autoscaling is off, the basic dimensions of each marker are given by the input data values in units of pixels. If autoscaling is on, the data values are gathered for all the currently visible points, and scaling factors are applied so that the largest ones will be a sensible size (a few tens of pixels). This autoscaling happens independently for the X and Y directions. The basic sizes can be further adjusted with the Scale slider.
Currently data values of zero always correspond to marker extent of zero, negative data values are not represented, and the mapping is linear. An absolute maximum size on markers is also imposed. Other options may be introduced in future.
Note the scaling to size is in terms of screen dimensions (pixels). For sizes that correspond to actual data values, the Error form may be more appropriate.
Example SizeXY plot
SizeXY form configuration panel
The configuration options are:
If auto-scaling is off, then markers will keep exactly the same screen size during pan and zoom operations; if it's on, then the visible sizes will change according to what other points are currently plotted.