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friturier / java-als

A Java implementation of Alternating Least Squares (ALS).

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Equation explanation

kostakis opened this issue · comments

commented

On batch ALS you update users and items factors with these equation
final double _uf = item_factors.getEntry(k, col) + this.alpha * (2.0 * error * user_factors.getEntry(row, k) - this.beta * item_factors.getEntry(k, col));

final double _if = user_factors.getEntry(row, k) + this.alpha * (2.0 * error * item_factors.getEntry(k, col) - this.beta * user_factors.getEntry(row, k));

I suppose beta is the regularization parameter?

But i cant understand how are your equation match to the ALS equations.
image

Can you give me some explanation on that?

The above equation is for explicit data, that's why it isn't using alpha.
I suppose you want to use this equation but i still cant see it.

image

Maybe it is non of the above equation can you show me in math how is your equation translated.