1 #!/usr/bin/env python

     2 # 11.1

     3 import os, sys

     4 sys.path += [os.getcwdu() + os.sep + ".." + os.sep + "python"]

     5 

     6 import pylab as pl

     7 from polyfuncs import poladd

     8 

     9 def recursion(A, dA, C, dC, j):

    10     Fo, dFo = C, dC

    11     Eo, dEo = 1, 0

    12     A_z = A[1:dA+1]

    13     dA_z = dA-1

    14     zi, dzi = 1, 0

    15     for i in range(j-1):

    16         if dFo == 0:

    17             Fn1 = 0

    18         else:

    19             Fn1 = Fo[1:dFo+1]

    20         dFn1 = max(dFo-1, 0)

    21         Fn2 = -Fo[0]*A_z

    22         dFn2 = dA-1

    23         Fn, dFn = poladd(Fn1, dFn1, Fn2, dFn2)

    24         Fn = Fn.squeeze()

    25         zi = pl.convolve(zi,[0,1])

    26         dzi += 1

    27         En2 = Fn[0]*zi

    28         dEn2 = dzi

    29         En, dEn = poladd(Eo, dEo, En2, dEn2)

    30         En = En.squeeze()

    31         Eo, dEo = En, dEn

    32         Fo, dFo = Fn, dFn

    33 

    34     if dFo == 0:

    35         Fn1 = 0

    36     else:

    37         Fn1 = Fo[1:dFo+1]

    38 

    39     dFn1 = max(dFo-1, 0)

    40     Fn2 = -Fo[0]*A_z

    41     dFn2 = dA-1

    42     Fn, dFn = poladd(Fn1, dFn1, Fn2, dFn2)

    43     Fn = Fn.squeeze()

    44     Ej, dEj = Eo, dEo

    45     Fj, dFj = Fn, dFn

    46 

    47 

    48     return Fj, dFj, Ej, dEj