question: public Matrix [ ] compute ( Matrix loghyper , Matrix X , Matrix Xstar ) { if ( loghyper . getColumnDimension ( ) != 1 || loghyper . getRowDimension ( ) != numParameters ( ) ) throw new IllegalArgumentException ( "Wrong number of hyperparameters, " + loghyper . getRowDimension ( ) + " instead of " + numParameters ( ) ) ; final double s2 = Math . exp ( 2 * loghyper . get ( 0 , 0 ) ) ; double [ ] a = new double [ Xstar . getRowDimension ( ) ] ; Arrays . fill ( a , s2 ) ; Matrix A = new Matrix ( a , Xstar . getRowDimension ( ) ) ; Matrix B = new Matrix ( X . getRowDimension ( ) , Xstar . getRowDimension ( ) ) ; return new Matrix [ ] { A , B } ; }
target:  Compute compute test set covariances