anchor.diff:  mu=-mu
   m=-m
   factor1=dsqrt((2*lambda+1)*fact(lambda-iabs(mu))/(2.d0*pi*fact(lambda+iabs(mu))))
  +if (factor1== 0.d0) return
   factor2=dsqrt((2*l+1)*fact(l-iabs(m))/(2.d0*pi*fact(l+iabs(m))))
  +if (factor2== 0.d0) return
   sum=0.d0
   sgn = 1.d0
   do k=0,(mu-1)/2
    do i=0,lambda-mu
  +  if (coef_pm(lambda,i+mu) == 0.d0) cycle
     sgnp = 1.d0
     do kp=0,(m-1)/2
      do ip=0,l-m
  +    if (coef_pm(l,ip+m) == 0.d0) cycle
       cylm=sgn*factor1*binom_func(mu,2*k+1)*fact(mu+i)/fact(i)*coef_pm(lambda,i+mu)
  +    if (cylm == 0.d0) cycle
       cylmp=sgnp*factor2*binom_func(m,2*kp+1)*fact(m+ip)/fact(ip)*coef_pm(l,ip+m)
  +    if (cylmp == 0.d0) cycle
       sum=sum+cylm*cylmp*bigA(mu-(2*k+1)+m-(2*kp+1)+k1,(2*k+1)+(2*kp+1)+k2,i+ip+k3)
      enddo
      sgnp = -sgnp
  
positive.code:                             array_coefs_B(k1p,1)*array_coefs_B(k2p,2)*array_coefs_B(k3p,3)* &
                              array_I_B(mup,lambdap,k1p,k2p,k3p)
                           
                           do k=1,kmax
                             ktot=k1+k2+k3+k1p+k2p+k3p+n_kl(k,l)
                             accu=accu+prodp*v_kl(k,l)*array_R(k,ktot,l,lambda,lambdap)
  
negative.code:    phi_DC0=datan2(d(2)/d2,d(1)/d2)
     
     do k=1,klocmax
       if (v_k(k) == 0.d0) cycle
       do k1=0,n_a(1)
         do k2=0,n_a(2)
           do k3=0,n_a(3)
             do k1p=0,n_b(1)
               do k2p=0,n_b(2)
                 do k3p=0,n_b(3)
                   if (array_coefs(k1,k2,k3,k1p,k2p,k3p) == 0.d0) cycle
                   do l=0,ntot
                     do m=-l,l
                       coef=ylm(l,m,theta_DC0,phi_DC0)
                       if (coef == 0.d0) cycle
                       ktot=k1+k2+k3+k1p+k2p+k3p+n_k(k)
                       if (array_R_loc(ktot,k,l) == 0.d0) cycle
                       prod=coef*array_coefs(k1,k2,k3,k1p,k2p,k3p)     &
                           *bigI(l,m,0,0,k1+k1p,k2+k2p,k3+k3p)
                       accu=accu+prod*v_k(k)*array_R_loc(ktot,k,l)
                     enddo
                   enddo
  