qpms/tests/transcoeff_cruzan.py

# [Xu] = Journal of computational physics 139, 137–165

from __future__ import print_function

def p_q(q, n, nu):
    return n + nu - 2*q

def qmax(M, n, mu, nu):
    return floor(min(n, nu, (n+nu-abs(M+mu))/2))

def Qmax(M, n, mu, nu): # [Xu](60)
    return floor(min(n, nu, (n+nu+1-abs(M+mu))/2))

def gaunta_p(M, n, mu, nu, p): # [Xu](5)
    #print (M,n,mu,nu,p, file=sys.stderr)
    return (-1)**(M+mu) * (2*p +1) * sqrt(
        factorial(n+M) * factorial(nu+mu) * factorial(p-M-mu)
      / factorial(n-M) / factorial(nu-mu) / factorial(p+M+mu)) * (
        wigner_3j(n, nu, p, 0, 0, 0) * wigner_3j(n, nu, p, M, mu, -M-mu))

def bCXcoeff(M, n, mu, nu, p): # [Xu](61)
    #print(M,n,mu,nu,p,file=sys.stderr)
    return (-1)**(M+mu) * (2*p + 3) * sqrt(
        factorial(n+M) * factorial(nu+mu) * factorial(p+1-M-mu)
      / factorial(n-M) / factorial(nu-mu) / factorial(p+1+M+mu)) * (
        wigner_3j(n, nu, p, 0, 0, 0) * wigner_3j(n, nu, p+1, M, mu, -M-mu))

def ACXcoeff(m, n, mu, nu, q): # [Xu](58)
    p = p_q(q,n,nu)
    return ((-1)**m * (2*nu + 1) * factorial(n+m) * factorial(nu-mu) / (
        2 * n * (n+1) * factorial(n-m) * factorial(nu+mu)) * I**p * 
        (n*(n+1) + nu*(nu+1) - p*(p+1)) * gaunta_p(-m,n,mu,nu,p))

def BCXcoeff(m, n, mu, nu, q): # [Xu](59)
    p = p_q(q,n,nu)
    return ((-1)**(m+1) * (2*nu + 1) * factorial(n+m) * factorial(nu-mu) / (
        2 * n * (n+1) * factorial(n-m) * factorial(nu+mu)) * I**(p+1) * 
        sqrt(((p+1)**2-(n-nu)**2) * ((n+nu+1)**2-(p+1)**2)) 
        * bCXcoeff(-m,n,mu,nu,p))

def printACXcoeffs(lMax, file=sys.stdout):
    for n in IntegerRange(lMax+1):
        for nu in IntegerRange(lMax+1):
            for m in IntegerRange(-n, n+1):
                for mu in IntegerRange(-nu, nu+1):
                    for q in IntegerRange(qmax(-m,n,mu,nu)):
                        #print(m, n, mu, nu, q, p_q(q,n,nu), file=sys.stderr)
                        coeff= ACXcoeff(m, n, mu, nu, q);
                        print(N(coeff, prec=53), 
                            ", // %d, %d, %d, %d, %d," % (m,n,mu,nu,q),
                            coeff,
                            file=file)
    return

def printBCXcoeffs(lMax, file=sys.stdout):
    for n in IntegerRange(lMax+1):
        for nu in IntegerRange(lMax+1):
            for m in IntegerRange(-n, n+1):
                for mu in IntegerRange(-nu, nu+1):
                    for q in IntegerRange(1, Qmax(-m,n,mu,nu) +1 ):
                        #print(m, n, mu, nu, q, p_q(q,n,nu), file=sys.stderr)
                        coeff= BCXcoeff(m, n, mu, nu, q);
                        print(N(coeff, prec=53), 
                            ", // %d, %d, %d, %d, %d," % (m,n,mu,nu,q),
                            coeff,
                            file=file)
    return

sphericalBessels = (None,
        spherical_bessel_J,
        spherical_bessel_Y,
        spherical_hankel1,
        spherical_hankel2
        )

# N.B. sage's gen_legendre_P _does_ include (-1)**m Condon-Shortley phase
# whereas formulae in [Xu] do not.
def trcoeff_ACX(m, n, mu, nu, besseltype, kd, th, fi, csphase=1): # [Xu](58)
    res = 0
    for q in range(qmax(-m,n,mu,nu)+1):
        p = p_q(q,n,nu)
        res += ACXcoeff(m,n,mu,nu,q) * sphericalBessels[besseltype](p,kd) * gen_legendre_P(p, mu-m, cos(th)) * (-csphase)**(mu-m) # compensate for csphase
    res *= exp(I*(mu-m)*fi)
    return res

def trcoeff_BCX(m, n, mu, nu, besseltype, kd, th, fi, csphase=1): # [Xu](59) 
    res = 0
    for q in range(Qmax(-m,n,mu,nu)+1):
        p = p_q(q,n,nu)
        res += BCXcoeff(m,n,mu,nu,q) * sphericalBessels[besseltype](p+1) * gen_legendre_P(p+1, mu-m, cos(th)) * (-csphase)**(mu-m)
    res *= exp(I*(mu-m)*fi)
    return res