question: private double [ ] [ ] xPrime ( int t ) { double [ ] [ ] x = new double [ 1 ] [ getNumLags ( ) * numVars ] ; for ( int i = 0 ; i < getNumLags ( ) ; i ++ ) { double [ ] [ ] yPrime = yPrime ( t - i - 1 ) ; System . arraycopy ( yPrime [ 0 ] , 0 , x [ 0 ] , i * numVars , numVars ) ; } return x ; }
target:  Constructs the x(t) vector.