function get_polzr_rainrate,dbz,d0,Nw,Mu,a_prime,MISSING=missing

    if(NOT KEYWORD_SET(missing)) then missing = -999.
;
; *** From eq. A.25 in Bring et al. 2004
;
    x1 = 6.0 * (3.67 + mu)^(4+mu)
    x2 = (3.67^4) * gamma(mu+4)
    f_mu = x1/x2
;
; *** From eq. A.23 in Bring et al. 2004
;
    x3 = f_mu * gamma(7+mu)
    x4 = (3.67+mu)^(7+mu)
    fz_mu = x3/x4
;
; *** From eq. A.24 in Bring et al. 2004
;
    x5  = !pi * 0.0006 * 3.78 * f_mu
    x6  = gamma(4.67 + mu) / (3.67+mu)^(4.67+mu)

    fr_mu = x5 * x6
    
    a_mu = fz_mu / (fr_mu^(1.5))
;
; *** Now, the new A parameter for the Z-R relation is given by:
; *** a' = a_mu/(Nw^1.5) 
;
    a_prime = a_mu/(Nw^0.5)
    rr =  get_zr_rain(dbz, a_prime, 1.5)

;    print,'dBZ,RR,Nw,A,F_mu,F_z,F_r: ',dbz,rr,nw,a_prime,f_mu,fz_mu,fr_mu

;    if(a_prime lt 100) then stop

    if(NOT finite(rr)) then begin
;        print,'Rain rate not finite!'
        rr = missing
    endif

    return,rr
    end