pi

pi is most commonly used to construct radian angle values for trigonometric functions. For example, you can encode the hour of day as a cyclic coordinate using (hour * 2 * pi()) / 24, or convert between degrees and radians using radians = degrees * pi() / 180.

Usage#

Syntax#

pi()

Parameters#

None.

Returns#

The double-precision value of π: approximately 3.14159265358979.

Example#

Use pi to encode the hour of day as a cyclic angle for time-based analysis.

Query

['sample-http-logs']
| extend hour_angle = (hourofday(_time) * 2 * pi()) / 24
| extend sin_hour = sin(hour_angle)
| extend cos_hour = cos(hour_angle)
| project _time, id, sin_hour, cos_hour

Run in Playground

Output

_time	id	sin_hour	cos_hour
2024-11-14 00:00:00	user-1	0.0000	1.0000
2024-11-14 06:00:00	user-2	1.0000	0.0000
2024-11-14 12:00:00	user-3	0.0000	-1.0000

sin: Returns the sine of an angle in radians. Combine with pi to encode cyclic signals.
cos: Returns the cosine of an angle in radians. Use together with sin and pi for cyclic coordinate encoding.
radians: Converts degrees to radians. Use it as an alternative to manually multiplying by pi() / 180.
degrees: Converts radians to degrees. Use it to express results from inverse trig functions in degrees instead of radians.
atan2: Returns the angle in radians between two coordinates. Its output range is (-π, π], so pi is a natural companion.

Other query languages#

Splunk SPL users

In Splunk SPL, pi() returns the same constant and works identically.

Splunk example

| eval angle = 2 * pi()

APL equivalent

print angle = 2 * pi()

ANSI SQL users

In ANSI SQL, PI() is a standard function in SQL Server and PostgreSQL that returns π.

SQL example

SELECT PI() AS pi_value