Functions whose Big O is exponential, *O(2 ^{n})*, grow so quickly
that they can hardly be plotted on a log-log graph.

If you find that your function cannot be plotted on a log-log
graph, try plotting it on a semi-log graph, where the *x* axis
is linear and the *y* axis is logarithmic.

An exponential function will produce a linear plot on a semi-log
graph. Such functions are considered to be * intractable*, i.e.
thay can only be computed when *n* is relatively small.