anchor.diff:      CALL NewQuNode(qA,init=.TRUE.)
       CALL SpAMM_Mat2Quad(A,qA)
       qA%Norm=SQRT(SpAMM_NormReduce(qA))
  +    CALL Filter_qutree(qA,1D-16)
     END FUNCTION Dense2Quad
   
     RECURSIVE SUBROUTINE SpAMM_Mat2Quad(A,qA)
  
positive.code:     ! Associated
      IF(ASSOCIATED(qA).AND.ASSOCIATED(qB))THEN
      ! Bounds
      IF(qA%Norm*qB%Norm*8D0**(HALF*DBLE(qA%Lev))<SpAMM_tolerance)RETURN
      ! Allocate
      IF(.NOT.ASSOCIATED(qC))CALL NewQuNode(qC,count=count)
      ! Boxing
  
negative.code:   END FUNCTION SpAMM_NormReduce
  
    FUNCTION NormReduce_dns(A) RESULT(norm)
      REAL(DOUBLE), DIMENSION(:,:) :: A
      REAL(DOUBLE) :: norm
      INTEGER :: I,J
  