Logarithm: log
Syntax
log ( op , num )
Input parameters
op |
the base of the logarithm |
num |
the number to which the logarithm is applied |
Examples of valid syntaxes
log ( DS_1, 2 )
log ( 1024, 2 )
Semantics for scalar operations
The operator log calculates the logarithm of num base op. For example:
log ( 1024, 2 ) gives 10log ( 1024, 10 ) gives 3.01Input parameters type
op
dataset { measure<number [value > 1] > _+ }
| component<number [value > 1] >
| number [value > 1]
num
component<integer [value > 0]>
| integer [value > 0]
Result type
result
dataset { measure<number> _+ }
| component<number>
| number
Additional Constraints
None.
Behavior
As for the invocations at Data Set level, the operator has the behaviour of the “Operators applicable on one Scalar Value or Data Set or Data Set Component”. As for the invocations at Component or Scalar level, the operator has the behaviour of the “Operators applicable on two Scalar Values or Data Sets or Data Set Components”, (see the section “Typical behaviours of the ML Operators”).
Examples
Given the operand dataset DS_1:
Input DS_1 (see structure)
Id_1 |
Id_2 |
Me_1 |
Me_2 |
|---|---|---|---|
10 |
A |
1024 |
0.7545 |
10 |
B |
64 |
13.45 |
11 |
A |
32 |
1.87 |
Example 1
DS_r := log ( DS_1, 2 );
results in (see structure):
Id_1 |
Id_2 |
Me_1 |
Me_2 |
|---|---|---|---|
10 |
A |
10.0 |
-0.4064071941354039 |
10 |
B |
6.0 |
3.749534267669262 |
11 |
A |
5.0 |
0.9030382701129122 |
Example 2
DS_r := DS_1 [ calc Me_1 := log (Me_1, 2) ];
results in (see structure):
Id_1 |
Id_2 |
Me_1 |
Me_2 |
|---|---|---|---|
10 |
A |
10.0 |
0.7545 |
10 |
B |
6.0 |
13.45 |
11 |
A |
5.0 |
1.87 |