Use the annotation option to add descriptive text that appears when the pointer hovers over a curve or a point.

plot(sin(x), x=0..2*Pi, annotation="a sine curve");

The annotation option allows you to add descriptive text to a 2-D curve or point plot. The term "point plot" in this context means a collection of points that are treated as a single plot element, such as that created by the plots:-pointplot or dataplot command.  The text, which can include mathematical expressions, appears when the pointer hovers over the plot element to which it is associated.

In the first calling sequence, t can be any Maple expression that can be typeset. See the plot/typesetting help page for more information about how such expressions can be specified. In this case, t is displayed whenever the pointer hovers over any part of the curve or point plot.

In the second calling sequence, A is an Array of $n$ values, where $n$ is the number of points defining a curve or in a single point plot. This form of the option does not work with curves consisting of disconnected parts, such as those formed using the discont option or the plots:-implicitplot command.

You can include the x-coordinate or y-coordinate associated with the location over which the pointer hovers in an annotation. To do this, use the name xcoordinate or ycoordinate as the annotation value or within a typeset structure as described on the plot/typesetting help page.

If you want to use a function of either the x-coordinate or y-coordinate, then use xcoordinate(p) or ycoordinate(p) where p is a procedure that accepts a numeric value and returns a numeric value, such as u->u^2.

To use a function of both coordinates, use xycoordinate(p) where p is a procedure that accepts two numeric values (the x-coordinate and y-coordinate, respectively) and returns a numeric value, such as (u,v)->u*v.

The number of digits displayed for the x-coordinate or y-coordinate can be specified by adding the digits=n option after the procedure p. Note that p can be omitted, as in xcoordinate(digits=5).

$\mathrm{plot}\left(x^2\,x=0..1\,\mathrm{annotation}=\mathrm{typeset}\left(''the\; function''\,x^2\right)\right)$

$\mathrm{dataplot}\left(\mathrm{Matrix}\left(\left[\left[0\,0\right]\,\left[1\,2\right]\,\left[2\,3\right]\,\left[3\,2\right]\,\left[4\,4\right]\right]\right)\,\mathrm{points}\,\mathrm{annotation}=\mathrm{Array}\left(\left[''January''\,''February''\,''March''\,''April''\,''May''\right]\right)\right)$

$\mathrm{plot}\left(x^2\,x=0..1\,\mathrm{annotation}=\mathrm{typeset}\left(''the\; square\; of''\,'\mathrm{xcoordinate}'\,''is''\,'\mathrm{ycoordinate}'\right)\right)$

$\mathrm{plot}\left(x^2\,x=0..1\,\mathrm{annotation}=\mathrm{typeset}\left(''the\; sum\; of\; x\; and\; y\; coordinates\; is''\,'\mathrm{xycoordinate}'\left(\left(x\,y\right)\mapsto x+y\,\mathrm{digits}=5\right)\right)\right)$

The annotation option was introduced in Maple 2017.

For more information on Maple 2017 changes, see Updates in Maple 2017.