Cbrt¶

Overview¶

The Cbrt expression computes the cube root of a numeric value. It extends UnaryMathExpression and delegates to Scala's math.cbrt function to calculate the cube root of the input expression.

Syntax¶

CBRT(expr)

// DataFrame API
import org.apache.spark.sql.functions.cbrt
cbrt(col("column_name"))

Arguments¶

Argument	Type	Description
child	Expression	The numeric expression to compute the cube root of

Return Type¶

Returns a DoubleType value representing the cube root of the input.

Supported Data Types¶

Supports all numeric data types as input:

ByteType
ShortType
IntegerType
LongType
FloatType
DoubleType
DecimalType

Algorithm¶

The expression evaluation follows these steps:

Inherits evaluation logic from UnaryMathExpression
Converts input value to Double type
Delegates computation to Scala's math.cbrt() function
Returns the computed cube root as a Double
Handles null propagation through the parent class

Partitioning Behavior¶

This expression preserves partitioning characteristics:

Does not affect data partitioning
No shuffle operations required
Can be evaluated locally on each partition
Maintains existing partition boundaries

Edge Cases¶

Null handling: Returns null if input is null
Negative numbers: Correctly handles negative inputs (cube root of negative numbers is negative)
Zero: Returns 0.0 for input value 0
Infinity: Returns positive infinity for positive infinity input, negative infinity for negative infinity input
NaN: Returns NaN for NaN input

Code Generation¶

This expression supports Tungsten code generation through inheritance from UnaryMathExpression, which implements the CodegenFallback trait for optimized runtime performance.

Examples¶

-- Basic usage
SELECT CBRT(27.0);
-- Result: 3.0

-- With negative numbers
SELECT CBRT(-8.0);
-- Result: -2.0

-- With column data
SELECT CBRT(volume) FROM measurements;

// DataFrame API usage
import org.apache.spark.sql.functions.cbrt

df.select(cbrt(col("volume")))

// With column alias
df.select(cbrt(col("volume")).alias("cube_root_volume"))