presto-main/src/main/java/io/prestosql/operator/scalar/MathFunctions.java/MathFunctions/log
class MathFunctions:    @Description("logarithm to given base")
    @ScalarFunction
    @SqlType(StandardTypes.DOUBLE)
    public static double log(@SqlType(StandardTypes.DOUBLE) double base, @SqlType(StandardTypes.DOUBLE) double number)
    {
        return Math.log(number) / Math.log(base);
    }