def int_connection_backward(modes,gamma=0.,delta=0.,G=0,D=0):
"""
Reverses the integer connection performed by int_connection
The input modes is a vector of (g+G,d+D) modes, and we wish to demote
them back to (g,d) modes.
"""
from numpy import append
from scipy import conj
from spyctral.jacobi.jfft import rmatrix_invert as jconnection_inv
G = int(G)
D = int(D)
if (G+D)>0:
N = modes.size
[cmodes,smodes] = sc_collapse(modes,N)
cmodes = jconnection_inv(cmodes,delta-1/2.,gamma-1/2.,D,G)
smodes = jconnection_inv(smodes,delta+1/2.,gamma+1/2.,D,G)
return sc_expand(cmodes,smodes,N)
else:
return modes.copy()
from spyctral.jacobi.jfft import rmatrix_invert as jconnection_inv
from spyctral.jacobi.jfft import rmatrix_apply_seq as jconnection
from spyctral.fourier.connection import sc_collapse, sc_expand
from numpy import append
from scipy import conj
G = gamma; D = delta; delta = 0; gamma=0;
NEven = (N%2)==0
ucopy = u.copy()
if NEven:
N += 1
ucopy[0] /= 2.
ucopy = append(ucopy,conj(ucopy[0]))
[cmodes,smodes] = sc_collapse(ucopy,N)
cmodes = jconnection(cmodes,delta-1/2.,gamma-1/2.,D,G)
smodes = jconnection(smodes,delta+1/2.,gamma+1/2.,D,G)
utemp = sc_expand(cmodes,smodes,N)
if NEven:
utemp[0] += conj(utemp[-1])
utemp = utemp[:-1]
cmodes3 = jconnection_inv(cmodes,delta-1/2.,gamma-1/2.,D,G)
smodes3 = jconnection_inv(smodes,delta+1/2.,gamma+1/2.,D,G)
u2 = sc_expand(cmodes3,smodes3,N)
utemp2 = int_connection(u,gamma=0.,delta=0.,G=G,D=D)
u3 = int_connection_backward(utemp2,gamma=0.,delta=0.,G=G,D=D)
