cos()#

relationalai.std.math
#cos(number: Number|Producer) -> Expression

Calculates the cosine of number, where number is specified in radians. If number is a Producer, cos() filters out any non-numeric values from the producer. Must be called in a rule or query context.

Parameters#

NameTypeDescription
numberProducer or Python Number objectThe angle in radians to calculate the cosine of.

Returns#

An Expression object.

Example#

Use cos() to calculate the cosine of an angle in radians:

#import relationalai as rai
from relationalai.std import math


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

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

with model.rule():
    Angle.add(id=1).set(value=0)
    Angle.add(id=2).set(value=3.14159)       # Approximately π
    Angle.add(id=3).set(value="INVALID")      # Non-numeric value


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

# Set a cos_value property to the cosine of each angle's value.
with model.rule():
    angle = Angle()
    angle.set(cos_value=math.cos(angle.value))

# Since cos() filters out non-numeric values, the cos_value property
# is not set for the angle with ID 3.
with model.query() as select:
    angle = Angle()
    response = select(angle.id, angle.cos_value)

print(response.results)
#    id  cos_value
# 0   1        1.0
# 1   2       -1.0
# 2   3        NaN

See Also#