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Use the cos function in APL to compute the cosine of an angle expressed in radians. The function accepts any real number and returns a value in the range [-1, 1]. cos is useful in observability and log analysis when you need to encode time-of-day or other cyclic patterns as a continuous numeric feature. For example, you can combine cos and sin to represent hour-of-day as a pair of cyclic coordinates, which preserves the circular distance between hours for anomaly detection or grouping.

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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.
In Splunk SPL, cos() is available in the eval command with the same behavior: it takes an angle in radians and returns the cosine.
| eval cos_val = cos(angle_rad)
In ANSI SQL, COS() is a standard mathematical function with identical semantics.
SELECT COS(angle_rad) AS cos_val FROM logs

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Usage

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Syntax

cos(x)

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Parameters

NameTypeRequiredDescription
xrealYesThe angle in radians.

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Returns

The cosine of x, a real number in the range [-1, 1].

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Example

Use cos to compute the cosine of an angle in radians. Query 
print result = cos(pi())
Run in Playground Output
result
-1
  • sin: Returns the sine. Use sin and cos together to produce a two-dimensional cyclic encoding of angles.
  • tan: Returns the tangent. Use it when you need the ratio of sine to cosine.
  • acos: Returns the arc cosine. Use it as the inverse of cos.
  • pi: Returns the constant π. Use it to compute angle values in radians.
  • radians: Converts degrees to radians. Use it to prepare angle inputs before calling cos.