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MaxCompute:LN

Last Updated:Jun 29, 2023

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

This section provides sample source data for you to understand how to use mathematical functions. In this topic, a table named mf_math_fun_t is created and data is inserted into the table. Sample statements:
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');
Query data from the mf_math_fun_t table. Sample statement:
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.