|curvefollow() displays a digital readout on the screen at the
location srow, scol in an 8 ´ 10 pixel
font and the cross hairs are displayed. Using the left and right arrow
keys, you can move the cross hairs from point to point on the
curve given by x and y (or r and theta
for polar plots). The <Home> and <End> keys may be used to move the
cursor to the start and end of the curve. Points may be marked and unmarked
with the <Ins> and <Del> keys, but nothing is entered into the TKF
file. The mode is exited by pressing the <Esc> key.
This mode allows visual selection and readout of the points along the
curve. In contrast to the curson() functions,
the displayed values for x and y are taken directly from the input
vectors, and hence are not subject to the roundoff
and discretization errors that occur if the screen point is converted
to user units.