- The
buttons under the graph allow various manipulations of
the graph coordinates.
- The text input fields for
*f* (*x*,*y*),
*g*(*x*,*y*),
div *F*, and
curl *F* can accept
a wide variety of expressions to represent functions.
- The text input fields for
*x* and *y*
can accept a real number in decimal notation.
- The point (
*x*,*y*) represents the center of a square, drawn
in blue.
- To change the size of the square, enter a value into the text
input field marked "s=" -- this value represents
the length of a side of the square.
- Four flow curve segments are drawn in yellow,
one from each corner of the
square, parameterized from 0 to
*t*.
- To change the lengths of the flow curves, enter a value into the text
input field marked "t=".
- The opposite endpoints of the curve segments are connected to form another
quadrilateral (not necessarily square), drawn in blue.
- Divergence is computed as
*f*_{x}+*g*_{y}.
- Curl is computed as
*g*_{x}-*f*_{y}.

©2002, Addison-Wesley. All rights reserved.