Probing
MathJet ships four probes for reading information at the cursor on both 2D and 3D graphs: the gauge probe for instantaneous coordinate readouts, the ruler probe for measuring differences between two points, the crosshair probe for axis-aligned coordinate display, and the magnifier probe for an enlarged view of a region.
Two universal shortcuts work with any probe active:
- Spacebar adds a data marker to the data point closest to the current mouse location.
- Escape disables the active probe immediately.
Gauge probe
Section titled “Gauge probe”The gauge probe gives you instantaneous visibility of coordinates or data item values at the current mouse position as you navigate over a plot area.
Enable or disable the gauge probe via the menu Plot → Probes → Gauge Probe or the corresponding tool button.
In two-dimensional charts, the gauge probe by default snaps to the nearest data point, draws a symbol at its location, and shows its coordinate values. The background color of the probe is automatically set to a “lighter” version of the graph that the data point is on. You can turn off the Snap to Data Points option and let the probe show coordinates at any location inside the plot area; while in that mode, you can still temporarily force the probe to snap to the nearest data point by holding down the left mouse button while dragging.
For three-dimensional charts, the gauge probe is visible only upon hitting a graphical object. In that case, the probe’s background color matches the graph at the mouse hit location. Turning Snap to Data Points on, or holding down the left mouse button, snaps the probe to the nearest data point just like on 2D charts.
Ruler probe
Section titled “Ruler probe”The ruler probe is commonly used for measuring the difference between two data points. Activate or deactivate it via Plot → Probes → Ruler Probe or the corresponding tool button.
Once the ruler probe is activated, a target symbol appears at the data point closest to the current mouse position. Clicking the left mouse button at the desired data point sets the anchor; you’ll see two data markers and two ruler-like lines appear. The anchor marker stays fixed while the probing marker moves with the mouse. The two rulers display the horizontal and vertical differences between the current mouse position and the anchor point. Clicking the left button again after moving the mouse elsewhere resets the anchor.
In a three-dimensional chart, there is only one direct ruler line between the two data markers, but the differences in all three dimensions are indicated along the line.
Crosshair probe
Section titled “Crosshair probe”The crosshair probe uses connector lines and value tags on the axis to display coordinates at the current mouse position. It also displays value tags on any intersecting graphs. Activate or deactivate via Plot → Probes → Crosshair Probe or the corresponding tool button.
In two-dimensional charts, the crosshair probe by default presents values for every graph at both the x and y planes — useful when you want to compare values across multiple graphs sharing the same x or y coordinate. You can toggle value tags on either the x or y planes via the drop-down menu. While the crosshair probe is active, pressing the spacebar adds X or Y markers to the chart easily.
For three-dimensional charts, the crosshair probe draws contour lines on surfaces at the current z-coordinate instead of straight lines parallel to the axes.
Magnifier probe
Section titled “Magnifier probe”The magnifier probe shows you an enlarged view of a region on the fly as you move the mouse over a chart. Enable or disable via Plot → Probes → Magnifier Probe or the corresponding tool button.
Once activated, a semi-transparent probing rectangle follows the cursor inside a plot. A larger scoping rectangle shows an enlarged view of the area covered by the probe.
You can adjust the size of the probing rectangle by scrolling the mouse wheel while holding the Shift key, which effectively changes the magnifying ratio. You can also choose to show data labels in the enlarged view via the drop-down menu, and you can change the location and size of the inset later.