anchor.diff:      do i=1,numnodes
          nt = OMP_GET_THREAD_NUM()
          call singrate(node_coordinates(i,:),node_coordinates(i,:),i,k_wave,centres,weights,nt)
  -       gauss(i,4) = sum(jacobian(nt + 1,:,:))
  +       gauss(i,4) = folding(i,i,one,dim_quad,nt)
       end do
       !$OMP END PARALLEL DO
     end function calcsing
  
positive.code:     do iz=1,dim_quad
         do ik=1,Nk
            tmp = farr(nthread,iz,ik)
            gtmp = gtmp + real(jacobian(nthread,iz,ik))*tmp
         end do
      end do
      foldingarr = gtmp
  
negative.code:     do iz=1,dim_quad
         do ik=1,Nk
            tmp = f(nodes(nthread,iz,ik,:),ip,jp)
            gtmp = gtmp + (jacobian(nthread,iz,ik))*tmp
         end do
      end do
      folding = gtmp
  