Many commands to find measures have a version ending in at (or atraw) which are used to interactively find and display the appropriate measure in a two-dimensional geometry screen. To use them, open a geometry screen with Alt-G and then select the appropriate measure from the Mode ▸ Measure menu. Once the mode is selected, then clicking on the names of the appropriate objects (or, if a point is being selected, a name will be automatically generated if clicking on an open point) with the mouse, and then clicking on another point will put the measurement at the point; if the mode is the version ending in at, then the measurement will have a label, if the mode is the version ending in atraw, then the measurement will appear without a label.
The commands with at and atraw versions are:
These commands can also be used from the command line. They are like the measurement command but take an extra argument, the point to display the measurement. When using the version ending in at, use names for the objects rather create the objects within the measurement command.
Examples.
The extract_measure command displays a measurement.
Example.
Input:
A:= point(-1); B:= point(1+i); C:= point(i); |
extract_measure(angleat(A,B,C,0.2i)) |
Output:
arctan | ⎛ ⎜ ⎜ ⎝ |
| ⎞ ⎟ ⎟ ⎠ |