question: public double [ ] skipTo ( final int index ) throws MathIllegalArgumentException { if ( index == 0 ) { Arrays . fill ( x , 0 ) ; } else { final int i = index - 1 ; final long grayCode = i ^ ( i > > 1 ) ; for ( int j = 0 ; j < dimension ; j ++ ) { long result = 0 ; for ( int k = 1 ; k <= BITS ; k ++ ) { final long shift = grayCode > > ( k - 1 ) ; if ( shift == 0 ) { break ; } final long ik = shift & 1 ; result ^= ik * direction [ j ] [ k ] ; } x [ j ] = result ; } } count = index ; return nextVector ( ) ; }
target:  Skip to the i-th point in the Sobol sequence. <p> This operation can be performed in O(1).