For log, the natural logarithm of the argument. For log10, the base 10 logarithm of the argument. For logn, the logarithm of the number in the given base.
Non-numeric arguments are treated as zero. Illegal values for the arguments will cause an error.
Gamma> log(2);
0.69314718055994528623
Gamma> log10(2);
0.30102999566398119802
Gamma> logn(8,2);
2.9999999999999995559
Gamma>