def get_moments_ij(m0, n=100, i=0, j=0, use_fortran=use_fortran):
""" Get the first n moments of a the |i><j| operator
using the Chebychev recursion relations"""
m = coo_matrix(m0, dtype=np.complex)
if use_fortran:
mus = kpmf90.get_moments_ij(m.row + 1, m.col + 1, m.data, n,
m.shape[0], i + 1, j + 1)
return mus
else:
mus = np.zeros(n, dtype=np.complex) # empty arrray for the moments
v = np.zeros(m.shape[0], dtype=np.complex)
v[i] = 1.0 # initial vector
v = np.matrix([v]).T # zero vector
am = v.copy()
a = m * v # vector number 1
bk = v[j] # scalar product
bk1 = a[j, 0] # scalar product
mus[0] = bk # mu0
mus[1] = bk1 # mu1
for ii in range(2, n):
ap = 2. * m * a - am # recursion relation
bk = ap[j, 0] # scalar product
mus[ii] = bk
am = a.copy() # new variables
a = ap.copy() # new variables
return mus
def get_moments_ij(m0,n=100,i=0,j=0,use_fortran=use_fortran):
""" Get the first n moments of a the |i><j| operator
using the Chebychev recursion relations"""
m = coo_matrix(m0,dtype=np.complex)
if use_fortran:
mus = kpmf90.get_moments_ij(m.row+1,m.col+1,m.data,n,m.shape[0],i+1,j+1)
return mus
else:
mus = np.zeros(n) # empty arrray for the moments
v = np.zeros(m.shape[0]) ; v[i] = 1.0 # initial vector
v = np.matrix([v]).T # zero vector
am = v.copy()
a = m*v # vector number 1
bk = v[j] # scalar product
bk1 = a[j,0] # scalar product
mus[0] = bk # mu0
mus[1] = bk1 # mu1
for ii in range(2,n):
ap = 2.*m*a - am # recursion relation
bk = ap[j,0] # scalar product
mus[ii] = bk
am = a.copy() # new variables
a = ap.copy() # new variables
return mus