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relationalai.std.math.acos()

acos(number: Number|Producer) -> Expression

Calculates the inverse cosine (arccosine) of number, where number is specified in radians and must be in the range -1 to 1. If number is a Producer, acos() filters out any non-number or invalid values from the producer. Must be called in a rule or query context.

Parameters

Name	Type	Description
`number`	`Producer` or Python `Number` object	The value to calculate the arccosine of, in the range `-1` to `1`.

Returns

An Expression object.

Example

Use acos() to calculate the arccosine of a value in radians:

import relationalai as rai
from relationalai.std import math


# =====
# SETUP
# =====

model = rai.Model("MyModel")
Satellite = model.Type("Satellite")

with model.rule():
    Satellite.add(id=1).set(name="SatA", orientation=0.5)
    Satellite.add(id=2).set(name="SatB", orientation=1.0)
    Satellite.add(id=3).set(name="SatC", orientation=-1.5)      # Out of range
    Satellite.add(id=4).set(name="SatD", orientation="INVALID") # Non-numeric value


# =======
# EXAMPLE
# =======

# Set an orientation_acos property to the arccosine of each satellite's orientation.
with model.rule():
    satellite = Satellite()
    satellite.set(orientation_acos=math.acos(satellite.orientation))

# Since acos() filters out non-numeric or out-of-range values, the orientation_acos
# property is not set for satellites with IDs 3 and 4.
with model.query() as select:
    satellite = Satellite()
    response = select(satellite.id, satellite.name, satellite.orientation_acos)

print(response.results)
#    id  name  orientation_acos
# 0   1  SatA          1.047198
# 1   2  SatB          0.000000
# 2   3  SatC               NaN
# 3   4  SatD               NaN

See Also