It probably amounts to much the same thing, but there is a log10() function available as a part of POSIX which is in the standard distribution.
use POSIX qw[log10];
print log10 312;
2.49415459401844
Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.