Arbitrary arrows can be placed on a plot using the set arrow command.
Syntax:
set arrow {<tag>} {from <sx>,<sy>{,<sz>}}
{to <ex>,<ey>{,<ez>}} {{no}head}
set noarrow {<tag>}
show arrow
Unspecified coordinates default to 0. The x, y, and z values are in the graph's coordinate system. The z coordinate is only used in splot commands. <tag> is an integer that identifies the arrow. If no tag is given, the lowest unused tag value is assigned automatically. The tag can be used to delete or change a specific arrow. To change any attribute of an existing arrow, use the set arrow command with the appropriate tag, and specify the parts of the arrow to be changed. Specifying nohead requests the arrow be drawn without a head (yielding a line segment). By default, arrows have heads.
Arrows outside the plotted boundaries are permitted but may cause device errors.
Examples:
To set an arrow pointing from the origin to (1,2), use:
set arrow to 1,2To set an arrow from (-10,4,2) to (-5,5,3), and tag the arrow number 3, use:
set arrow 3 from -10,4,2 to -5,5,3To change the preceding arrow begin at 1,1,1, without an arrow head, use:
set arrow 3 from 1,1,1 noheadTo delete arrow number 2 use:
set noarrow 2To delete all arrows use:
set noarrowTo show all arrows (in tag order) use:
show arrow