Definition of log (base n) is that log n(x) = y where n^y = x for all values
of x and y. n is the base.
So a base 10 log would be reversed by doing 10^x=y. If we know x, we use
the exponential operation; if we know y we use log(y) = x. For ln (natural
logs, base e, e is approx. 2.818), use e^x=y.
Hope this explains things.
Best Wishes,
Chris Travers
