add_date_int add_interval_interval add_timestamptz_interval bool_in bool_out cstring2text date_in date_out date_to_timestamp date_to_timestamptz float_exp float_ln float_log10 float_round interval_cmp interval_in interval_make interval_out minus_date_date minus_date_int minus_timestamptz_interval minus_timestamptz_timestamptz mul_interval_double text2cstring text_cmp text_copy text_initcap text_lower text_out text_upper textcat_text_text time_in time_out timestamp_in timestamp_out timestamp_to_date timestamptz_in timestamptz_out timestamptz_shift timestamptz_to_date

float_ln() double float_ln ( double  d ) Return the natural logarithm of a double. Parameters [in] d Value Note PostgreSQL function: dlog1(PG_FUNCTION_ARGS)