#!/usr/bin/env python
# 11.1
import os, sys
sys.path += [os.getcwdu() + os.sep + ".." + os.sep + "python"]

import pylab as pl
from polyfuncs import poladd

def recursion(A, dA, C, dC, j):
    Fo, dFo = C, dC
    Eo, dEo = 1, 0
    A_z = A[1:dA+1]
    dA_z = dA-1
    zi, dzi = 1, 0
    for i in range(j-1):
        if dFo == 0:
            Fn1 = 0
        else:
            Fn1 = Fo[1:dFo+1]
        dFn1 = max(dFo-1, 0)
        Fn2 = -Fo[0]*A_z
        dFn2 = dA-1
        Fn, dFn = poladd(Fn1, dFn1, Fn2, dFn2)
        Fn = Fn.squeeze()
        zi = pl.convolve(zi,[0,1])
        dzi += 1
        En2 = Fn[0]*zi
        dEn2 = dzi
        En, dEn = poladd(Eo, dEo, En2, dEn2)
        En = En.squeeze()
        Eo, dEo = En, dEn
        Fo, dFo = Fn, dFn

    if dFo == 0:
        Fn1 = 0
    else:
        Fn1 = Fo[1:dFo+1]

    dFn1 = max(dFo-1, 0)
    Fn2 = -Fo[0]*A_z
    dFn2 = dA-1
    Fn, dFn = poladd(Fn1, dFn1, Fn2, dFn2)
    Fn = Fn.squeeze()
    Ej, dEj = Eo, dEo
    Fj, dFj = Fn, dFn


    return Fj, dFj, Ej, dEj