org.apache.spark.ml.recommendation

Class ALS.NormalEquation

Object

org.apache.spark.ml.recommendation.ALS.NormalEquation

All Implemented Interfaces:

java.io.Serializable

Enclosing class:

ALS

public static class ALS.NormalEquation
extends Object
implements scala.Serializable

Representing a normal equation to solve the following weighted least squares problem:

minimize \sum,,i,, c,,i,, (a,,i,,^T^ x - b,,i,,)^2^ + lambda * x^T^ x.

Its normal equation is given by

\sum,,i,, c,,i,, (a,,i,, a,,i,,^T^ x - b,,i,, a,,i,,) + lambda * x = 0.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ALS.NormalEquation(int k)

Method Summary

Methods

Modifier and Type	Method and Description
ALS.NormalEquation	add(float[] a, double b, double c) Adds an observation.
double[]	ata() A^T^ * A
double[]	atb() A^T^ * b
int	k()
ALS.NormalEquation	merge(ALS.NormalEquation other) Merges another normal equation object.
void	reset() Resets everything to zero, which should be called after each solve.
int	triK() Number of entries in the upper triangular part of a k-by-k matrix.

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ALS.NormalEquation

public ALS.NormalEquation(int k)

Method Detail

k

public int k()

triK

public int triK()

Number of entries in the upper triangular part of a k-by-k matrix.

ata

public double[] ata()

A^T^ * A

atb

public double[] atb()

A^T^ * b

add

public ALS.NormalEquation add(float[] a,
                     double b,
                     double c)

Adds an observation.

merge

public ALS.NormalEquation merge(ALS.NormalEquation other)

Merges another normal equation object.

reset

public void reset()

Resets everything to zero, which should be called after each solve.