MaxCompute:LN

Static values

-- Returns 0.0
SELECT ln(1);

-- Returns 1.144729868791239
SELECT ln(3.1415926);

-- Returns 2.302585092994046
SELECT ln(10);

-- Returns 4.605170185988091
SELECT ln(100);

-- Returns NULL (negative input)
SELECT ln(-1);

-- Returns NULL
SELECT ln(null);

Table data

The following examples use the mf_math_fun_t sample table. To create and populate the table, run:

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');

Calculate the natural logarithm across all numeric columns:

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                |
+--------------------+----------------------+---------------------+---------------------+