Use the sqrt function in APL to compute the square root of a non-negative numeric value.

sqrt is useful whenever you want to compress large numeric ranges, compute root-mean-square values, normalize metrics, or undo a squared transformation. It's equivalent to pow(x, 0.5) but is more concise for the square-root case.

If the input is negative, sqrt returns NaN (Not a Number). APL represents NaN as null in query results. Use isnan to filter these values before aggregating or charting.

#For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

['sample-http-logs']
| extend root_duration = sqrt(req_duration_ms)

['sample-http-logs']
| extend root_duration = sqrt(req_duration_ms)

#Usage

#Syntax

sqrt(x)

#Parameters

#Returns

Returns the square root of x.

If x is negative, the function returns NaN, which APL represents as null in query results. Use isnan to check for this condition.

#Examples

#Compute the square root of request duration

Use sqrt to normalize request durations by taking their square root, compressing the range of large values.

Query

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

Run in Playground

Output

#Detect NaN from negative inputs

When input values are negative, sqrt returns NaN. APL displays NaN as null. Use isnan to identify and handle these rows.

Query

['sample-http-logs']
| extend shifted = req_duration_ms - 500
| extend root_shifted = sqrt(shifted)
| extend is_invalid = isnan(root_shifted)
| project _time, id, shifted, root_shifted, is_invalid

Run in Playground

Output

#List of related functions

• pow: Raises a value to an arbitrary power. sqrt(x) is equivalent to pow(x, 0.5).
• isnan: Returns true when a value is NaN. Use it to detect null results from sqrt on negative inputs.
• abs: Returns the absolute value. Use it to ensure inputs are non-negative before passing them to sqrt.
• exp: Returns e^x. Use it when the inverse operation of log is needed rather than a root.
• log: Returns the natural logarithm. Use it alongside sqrt when working in log space.