The macros \drawline
and \drawvector
provide the capability found in LaTeX's
picture mode to draw slanted lines and vectors of certain directions.
Both of these macros take three arguments: two integer arguments to
specify the direction of the line or vector, and one argument to specify
its length. For example, `\drawvector(-4,1){60pt}' produces the
vector
which lies in the 2d quadrant, has a slope of minus 1/4, and a width of
60 pt.
Note that if an \hbox is placed around \drawline or
\drawvector, then the width of the \hbox will be the
positive dimension specified in the third argument, except when a
vertical line or vector is specified, e.g.,
\drawline(0,1){1in}, which has zero width. If the specified
direction lies in the 1st or 2d quadrant (e.g., (1,1) or
(-2,3)), then the \hbox will have positive height and zero
depth. Conversely, if the specified direction lies in the 3d or 4th
quadrant (e.g., (-1,-1) or (2,-3)), then the \hbox
will have positive depth and zero height.
There are a finite number of directions that can be specified. For
\drawline, the absolute value of each integer defining the
direction must be less than or equal to six, i.e., (7,-1) is
incorrect, but (6,-1) is acceptable. For \drawvector, the
absolute value of each integer must be less than or equal to four.
Furthermore, the two integers cannot have common divisors; therefore, if
a line with slope 2 is desired, say (2,1) instead of
(4,2). Also, specify (1,0) instead of, say, (3,0)
for horizontal lines and likewise for vertical lines.
Finally, these macros depend upon the LaTeX font line10. If
your site doesn't have this font, ask your system administrator to get
it. Future enhancements will include macros to draw dotted lines and
dotted vectors of various directions.