abs

Use the abs function in APL to compute the absolute value of a numeric expression or timespan. The function removes the sign from the input, so it always returns a non-negative result.

abs is useful whenever you care about the magnitude of a deviation rather than its direction. For example, you can use it to measure how far a request latency strays from a baseline, or how large a fluctuation in a metric is regardless of whether it's above or below the expected value.

Usage

Syntax

abs(x)

Parameters

Returns

The absolute value of x. The return type matches the input type.

Example

Use abs to find how far each request's duration deviates from a 200 ms baseline.

Query

['sample-http-logs']
| extend deviation = abs(req_duration_ms - 200)
| project _time, id, req_duration_ms, deviation
| order by deviation desc

Output

List of related functions

• round: Rounds a value to a specified number of decimal places. Use it when you want to reduce precision rather than compute magnitude.
• sign: Returns the sign of a numeric value (+1, 0, or -1). Use it when you want to know direction rather than magnitude.
• sqrt: Returns the square root. Use it to compute the root-mean-square of deviations for standard deviation calculations.
• pow: Raises a value to a power. Use it to square deviations when computing variance.
• log: Returns the natural logarithm. Use it when you need to work on a logarithmic scale rather than with raw magnitudes.

Other query languages