is the returan value this function( Matrix WALSEngine::computeXtX(const Matrix& X) ) to get the transpose matrix of the original matrix?

[jackyhawk]

Matrix WALSEngine::computeXtX(const Matrix& X)

WALSEngine::computeXtX

[jackyhawk]

@eggie5 @albietz @MattPD
Thanks very much

[jackyhawk]

if it's not the matrix transpose, then what computeXtX is used to ?

it seems that computeXtX wants to get a square matrix(whose rank is the column size of the original matrix), and its values are filled with the sum of the value in each node/item multiplies all the other value(node) in the original matrix.

Thanks very much

[jackyhawk]

any suggestion?

[abietti]

Hi @jackyhawk,
As the name suggests, computeXtX computes X' * X for some matrix X, where X' denotes the transpose of X.

[jackyhawk]

Thanks very much.
and as I change the factor length from 500 to 200, it runs very fast now.