Contents:
Computes the logarithm of the first argument with a base of the second argument.
- First argument can be a Decimal or Integer literal or a reference to a column containing numeric values.
- Second argument, the base, must be an Integer value or column reference.
Basic Usage
Numeric literal example:
derive type:single value: LOG(49, 7)
Output: Generates a column containing the value of 7x = 49, which evaluates to 2.
Column reference example:
derive type:single value: LOG(MyValue, 5) as: 'log_MyValue'
Output: Generates the new log_MyValue column containing the exponent that raises 5 to yield the MyValue column.
Syntax and Arguments
derive type:single value: LOG(result_numeric_value, base_numeric_value)
| Argument | Required? | Data Type | Description |
|---|---|---|---|
| result_numeric_value | Y | string, decimal, or integer | Name of column or Decimal or Integer literal that is generated by the LOG function |
| base_numeric_value | Y | string, decimal, or integer | Name of column or Decimal or Integer literal that serves as the base for computing the LOG function |
For more information on syntax standards, see Language Documentation Syntax Notes.
result_numeric_value
Name of the column or numeric literal. Value must be greater than 0.
- Missing input values generate missing results.
- Literal numeric values should not be quoted. Quoted values are treated as strings.
- Multiple columns and wildcards are not supported.
Usage Notes:
| Required? | Data Type | Example Value |
|---|---|---|
| Yes | String (column reference) or Integer or Decimal literal | 49 |
base_numeric_value
Name of the column or Integer literal that is used for the exponential calculation.
NOTE: This base value must be a positive integer. If this value is not specified, 10 is used as the base value.
- Missing input values generate missing results.
- Literal numeric values should not be quoted. Quoted values are treated as strings.
- Multiple columns and wildcards are not supported.
Usage Notes:
| Required? | Data Type | Example Value |
|---|---|---|
| No | String (column reference) or Integer or Decimal literal | 7 |
Tip: For additional examples, see Common Tasks.
Examples
Example - Exponential functions
EXP- ex . See EXP Function.LN- natural logarithm of the above. See LN Function.LOG- 10x. See LOG Function.POW- XY. The value X raised to the power Y. See POW Function.
Source:
| rowNum | X |
|---|---|
| 1 | -2 |
| 2 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 3 |
| 7 | 4 |
| 8 | 5 |
Transform:
derive type:single value: EXP (X) as: 'expX'
derive type:single value: LN (expX) as: 'ln_expX'
derive type:single value: LOG (X) as: 'logX'
derive type:single value: POW (10,logX) as: 'pow_logX'
Results:
In the following, (null value) indicates that a null value is generated for the computation.
| rowNum | X | expX | ln_expX | logX | pow_logX |
|---|---|---|---|---|---|
| 1 | -2 | 0.1353352832366127 | -2 | (null value) | (null value) |
| 2 | -1 | 0.1353352832366127 | -0.9999999999999998 | (null value) | (null value) |
| 3 | 0 | 1 | 0 | (null value) | 0 |
| 4 | 1 | 2.718281828459045 | 1 | 0 | 1 |
| 5 | 2 | 7.3890560989306495 | 2 | 0.30102999566398114 | 1.9999999999999998 |
| 6 | 3 | 20.085536923187668 | 3 | 0.47712125471966244 | 3 |
| 7 | 4 | 54.59815003314423 | 4 | 0.6020599913279623 | 3.999999999999999 |
| 8 | 5 | 148.41315910257657 | 5 | 0.6989700043360187 | 4.999999999999999 |
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