ZEROLINES command

Syntax: | `ZEROLINES`
Qualifiers: | `\HORIZONTAL, \VERTICAL`
Defaults: | both horizontal and vertical lines drawn
Examples: | `ZEROLINES ZEROLINES\HORIZONTAL ZEROLINES\VERTICAL`

The `ZEROLINES` command draws horizontal and/or vertical lines on a graph through `(0,0)` depending on the qualifier that is used.

qualifier | result
`\HORIZONTAL` | a line is drawn through (0,0) parallel to the x-axis, from the left edge to the right edge
`\VERTICAL` | a line is drawn through (0,0) parallel to the y-axis, from the bottom edge to the top edge

Examples

The following script produces the figure below.

     WINDOW 5
     SCALES -5 5 -5 5
     GRAPH\AXESONLY
     SET CURVECOLOR RED
     ZEROLINES
     WINDOW 7
     SCALES -5 5 -5 5
     GRAPH\AXESONLY
     SET CURVECOLOR RED
     ZEROLINES/HORIZONTAL
     WINDOW 12 25 0 75 50
     SCALES -5 5 -5 5
     GRAPH\AXESONLY
     SET CURVECOLOR RED
     ZEROLINES/VERTICAL