Calculate Natural Logarithm of Values

Calculate the natural logarithm of a double field using the math:log() function

Query

flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1["Expression"] 2["Expression"] result{{Result Set}} repo --> 1 1 --> 2 2 --> result

logscale

x := 7.389056099
        | math:log(x, as=log_result)

Introduction

The math:log() function can be used to calculate the natural logarithm (base e) of a double field (a field containing a double-precision floating-point number). This function determines the exponent needed to raise Euler's number e (approximately 2.718281828) to obtain the given number. Euler's number e is a fundamental mathematical constant that naturally occurs in calculations involving continuous growth or decay.

In this example, the math:log() function is used to calculate the natural logarithm of a double-precision value, showing how many times you need to multiply Euler's number e by itself to get that value. The value e is a transcendental number that serves as the base of natural logarithms and exponential functions.

Step-by-Step

Starting with the source repository events.
flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1["Expression"] 2["Expression"] result{{Result Set}} repo --> 1 1 --> 2 2 --> result style 1 fill:#ff0000,stroke-width:4px,stroke:#000;
logscale
```
x := 7.389056099
```
Assigns the double-precision floating-point value 7.389056099 to a field named x. This value will be used to calculate its natural logarithm. Note the decimal point indicating a floating-point number.
flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 1["Expression"] 2["Expression"] result{{Result Set}} repo --> 1 1 --> 2 2 --> result style 2 fill:#ff0000,stroke-width:4px,stroke:#000;
logscale
```
| math:log(x, as=log_result)
```
Calculates the natural logarithm of the double-precision value in field x and returns the result in a new field named log_result as a double-precision number. If the as parameter is not specified, the result is returned in a field named _log as default.
Event Result set.

Summary and Results

The query is used to calculate the natural logarithm of a double-precision value, which is useful in analyzing exponential growth or decay in natural systems.

This query is useful, for example, to analyze natural growth patterns, normalize exponential data, or measure rates of continuous change where precise floating-point calculations are required.

Sample output from the incoming example data:

log_result
2.000000

The result shows that the natural logarithm of 7.389056099 = 2.000000, meaning that e^² 蝶 7.389056099. This indicates that you need to multiply e by itself 2 times to get approximately 7.389056099.

Some other examples with double-precision values:

natural logarithm of 1.0 = 0.000000 (e^⁰ = 1)
natural logarithm of 2.718281828 = 1.000000 (e^¹ = e)
natural logarithm of 20.085536923 = 3.000000 (e^³ 蝶 20.085536923)
natural logarithm of 0.367879441 = -1.000000 (e^⁻¹ 蝶 0.367879441)

Euler's number e is a fundamental mathematical constant discovered by the mathematician Leonhard Euler. It is irrational and transcendental, and appears naturally in many mathematical calculations, particularly those involving continuous compound interest, exponential growth, or decay. When used as the base for logarithms, it creates natural logarithms, which have the unique property that their derivative is 1/x, making them especially useful in calculus and natural sciences.

Examples Library