log(m, n)

Returns the natural logarithm (base m) of a number n. The values m and n can be any positive, non-zero numeric value in the range 0 < m, n <= 1e308 and m ≠ 1. The smallest value for m or n that will not produce 0 is log(10, 0.3e-323). This function can only be used in a foreach statement.

q = foreach q generate log(10, Population) as Population;
q = filter q by log(10, Population) < 15;