log10 ↗

Use the log10() function to calculate the base-10 (common) logarithm of a numeric value.

Syntax

log10(<number>)

Parameters

Name Type Required Description
number integer, float Yes The numeric value for which to calculate the base-10 logarithm. The value must be greater than 0.

Returns

Type: float

Description: The log10() function returns the base-10 logarithm of the input value. If the input is null, zero, or negative, the function returns null or NaN.

Usage notes

  • Input type: XQL doesn't support NaN or infinite values as input and these value types also can not be returned.
  • Valid Input Range: The input number must be strictly greater than 0. The base-10 logarithm is undefined for zero and negative numbers.
  • Zero Input: log10(0) returns negative infinity or null.
  • Negative Input: log10(x) for x < 0 returns NaN or null.
  • Null Handling: If the input expression is null, the function returns null.
  • Key Values: log10(1) returns 0.0, log10(10) returns 1.0, log10(100) returns 2.0, log10(1000) returns 3.0.
  • Relationship: log10(x) is equivalent to log(x, 10).
  • Common Use Cases: This function is typically used within the alter stage for decibel calculations, order-of-magnitude analysis, pH calculations, and logarithmic scaling of data.

Examples

Example 1: Calculate base-10 logarithm of literal values

Goal: Calculate the base-10 logarithm for specific numeric literals to verify known mathematical results.

XQL code:

dataset = xdr_data
| limit 1
| alter result1 = log10(1), result2 = log10(100), result3 = log10(1000)
| fields result1, result2, result3

Explanation: log10(1) returns 0.0, log10(100) returns 2.0 (since 10^2 = 100), and log10(1000) returns 3.0 (since 10^3 = 1000).

Output:

RESULT1 RESULT2 RESULT3
0.0 2.0 3.0

Example 2: Calculate base-10 logarithm from a field value

Goal: Calculate the base-10 logarithm of values stored in a dataset field to determine their order of magnitude.

XQL code:

config timeframe = 1d
| dataset = sample_xql_raw
| filter numeric_value > 0
| alter log10_result = log10(numeric_value)
| alter order_of_magnitude = floor(log10_result)
| fields event_id, numeric_value, log10_result, order_of_magnitude
| limit 3

Explanation: This query computes the base-10 logarithm for each positive value in numeric_value, then uses floor() to determine the order of magnitude. For example, a value of 500 has log10 ≈ 2.699, so its order of magnitude is 2 (hundreds).

Output:

EVENT_ID NUMERIC_VALUE LOG10_RESULT ORDER_OF_MAGNITUDE
101 5.0 0.69897 0
102 500.0 2.69897 2
103 10000.0 4.0 4

Example 3: Use log10 for decibel calculation

Goal: Calculate a decibel-like ratio using the base-10 logarithm.

XQL code:

config timeframe = 1d
| dataset = sample_xql_raw
| filter numeric_value > 0 and duration_seconds > 0
| alter ratio = divide(numeric_value, duration_seconds)
| alter decibel_ratio = multiply(10, log10(ratio))
| fields event_id, numeric_value, duration_seconds, ratio, decibel_ratio
| limit 3

Explanation: This query calculates a decibel-like ratio using the formula 10 * log10(ratio), which is a common pattern in signal processing and audio engineering.

Output:

EVENT_ID NUMERIC_VALUE DURATION_SECONDS RATIO DECIBEL_RATIO
101 100.0 1.0 100.0 20.0
102 50.0 5.0 10.0 10.0
103 1000.0 10.0 100.0 20.0