Calculates the natural logarithm of number.
Syntax
double|decimal ln(<number>)Parameters
number: required. A value of the DOUBLE or DECIMAL type. If the input value is of the STRING or BIGINT type, the value is implicitly converted into a value of the DOUBLE type before calculation.
Return value
A value of the DOUBLE or DECIMAL type is returned. The return value varies based on the following rules:
If the value of number is of the DOUBLE or DECIMAL type, a value of the same type is returned.
If the value of number is of the STRING or BIGINT type, a value of the DOUBLE type is returned.
If the value of number is a negative value or 0, null is returned.
If the value of number is null, null is returned.
Sample data
create table if not exists mf_math_fun_t(
int_data int,
bigint_data bigint,
double_data double,
decimal_data decimal,
float_data float,
string_data string
);
insert into mf_math_fun_t values
(null, -10, 0.525, 0.525BD, cast(0.525 as float), '10'),
(-20, null, -0.1, -0.1BD, cast(-0.1 as float), '-10'),
(0, -1, null, 20.45BD, cast(-1 as float), '30'),
(-40, 4, 0.89, null, cast(0.89 as float), '-30'),
(5, -50, -1, -1BD, null, '50'),
(-60, 6, 1.5, 1.5BD, cast(1.5 as float), '-50'),
(-1, -70, -7.5, -7.5BD, cast(-7.5 as float),null ),
(-80, 1, -10.2, -10.2BD, cast(-10.2 as float), '-1' ),
(9, -90, 2.58, 2.58BD, cast(2.58 as float), '0'),
(-100, 10, -5.8, -5.8BD, cast(-5.8 as float), '-90');select * from mf_math_fun_t;
-- The following result is returned:
+------------+-------------+-------------+--------------+------------+-------------+
| int_data | bigint_data | double_data | decimal_data | float_data | string_data |
+------------+-------------+-------------+--------------+------------+-------------+
| NULL | -10 | 0.525 | 0.525 | 0.525 | 10 |
| -20 | NULL | -0.1 | -0.1 | -0.1 | -10 |
| 0 | -1 | NULL | 20.45 | -1.0 | 30 |
| -40 | 4 | 0.89 | NULL | 0.89 | -30 |
| 5 | -50 | -1.0 | -1 | NULL | 50 |
| -60 | 6 | 1.5 | 1.5 | 1.5 | -50 |
| -1 | -70 | -7.5 | -7.5 | -7.5 | NULL |
| -80 | 1 | -10.2 | -10.2 | -10.2 | -1 |
| 9 | -90 | 2.58 | 2.58 | 2.58 | 0 |
| -100 | 10 | -5.8 | -5.8 | -5.8 | -90 |
| NULL | -10 | 0.525 | 0.525 | 0.525 | 10 |
| -20 | NULL | -0.1 | -0.1 | -0.1 | -10 |
| 0 | -1 | NULL | 20.45 | -1.0 | 30 |
| -40 | 4 | 0.89 | NULL | 0.89 | -30 |
| 5 | -50 | -1.0 | -1 | NULL | 50 |
| -60 | 6 | 1.5 | 1.5 | 1.5 | -50 |
| -1 | -70 | -7.5 | -7.5 | -7.5 | NULL |
| -80 | 1 | -10.2 | -10.2 | -10.2 | -1 |
| 9 | -90 | 2.58 | 2.58 | 2.58 | 0 |
| -100 | 10 | -5.8 | -5.8 | -5.8 | -90 |
+------------+-------------+-------------+--------------+------------+-------------+Example: static data
-- The return value is 1.144729868791239.
select ln(3.1415926);
-- The return value is null.
select ln(null);Example: table data
Calculate the natural logarithm value based on the sample data. Sample statement:
select ln(bigint_data) as bigint_new, ln(double_data) as double_new, ln(decimal_data) as decimal_new, ln(string_data) as string_new from mf_math_fun_t;The following result is returned:
+--------------------+----------------------+---------------------+---------------------+
| bigint_new | double_new | decimal_new | string_new |
+--------------------+----------------------+---------------------+---------------------+
| NULL | -0.6443570163905132 | -0.6443570163905132 | 2.302585092994046 |
| NULL | NULL | NULL | NULL |
| NULL | NULL | 3.017982882488811 | 3.4011973816621555 |
| 1.3862943611198906 | -0.11653381625595151 | NULL | NULL |
| NULL | NULL | NULL | 3.912023005428146 |
| 1.791759469228055 | 0.4054651081081644 | 0.4054651081081644 | NULL |
| NULL | NULL | NULL | NULL |
| 0.0 | NULL | NULL | NULL |
| NULL | 0.9477893989335261 | 0.9477893989335261 | NULL |
| 2.302585092994046 | NULL | NULL | NULL |
+--------------------+----------------------+---------------------+---------------------+Related functions
LN is a mathematical function. For more information about functions related to data computing and conversion, see Mathematical functions.