This applet lets the student work with the epsilon-delta definition of
Recall that when we say the limit as x approaches a of f(x) is L we
mean that for every epsilon > 0 there is a delta > zero with
|f(x) - L| < epsilon whenever 0 < | x-a | < delta.
This definition is often hard for students to understand, so it is
useful to do a visual translation: the limit as x approaches a of f(x) is L means for every height epsilon
we can find a width delta so that for a box centered at (a,L) going up
and down epsilon and right and left delta, the function only escapes
through the sides of the box rather than the top and bottom.
Notes on use of the applet:
Dragging on the graph produces a box for zooming in.
Functions can be loaded either from the drop down menu at the top
of the applet, or typed in at the bottom of the applet.
the values of a and L can be controlled either by slider or by
typing in the text fields.