`\vector`

Synopsis:

\vector(x_run,y_rise){travel}

Draw a line ending in an arrow. The slope of that line is: it
vertically rises `y_rise` for every horizontal `x_run`. The
`travel` is the total horizontal change—it is not the
length of the vector, it is the change in *x*. In the special case
of vertical vectors, if (`x_run`,`y_rise`)=(0,1), then
`travel` gives the change in *y*.

For an example see `picture`

.

For elaboration on `x_run` and `y_rise` see `\line`

. As
there, the values of `x_run` and `y_rise` are limited. For
`\vector`

you must chooses integers between −4 and 4,
inclusive. Also, the two you choose must be relatively prime. Thus,
`\vector(2,1){4}`

is acceptable but `\vector(4,2){4}`

is
not (if you use the latter then you get a sequence of arrowheads).