def square(vectors, var=None, full=False):
"""
calculates the eigen-vectors and eigen-values of the covariance matrix that
would be produced by multiplying out A.var*numpy.array(A.vectors.H)*A.vectors
without necessarily calculating the covariance matrix itself.
It is also setup to handle vectors with infinite variances.
origionally the idea came from these two line on wikipedia:
http://en.wikipedia.org/wiki/Square_root_of_a_matrix:
'''if T = A*A.H = B*B.H, then there exists a unitary U s.t. A = B*U'''
http://en.wikipedia.org/wiki/Unitary_matrix
'''In mathematics, a unitary matrix is an nxn complex matrix U satisfying
the condition U.H*U = I, U*U.H = I'''
*********************************
A better description for all this is the compact singular value decomposition.
http://en.wikipedia.org/wiki/Singular_value_decomposition#Compact_SVD
but here I only need one of the two sets of vectors, so I actually calculate the smaller of
the two possible covariance marixes and, and then it's eigen-stuff.
"""
if var is None:
var = numpy.ones(vectors.shape[0])
finite = numpy.isfinite(var) & numpy.isfinite(vectors.asarray()).all(1)
infinite = ~finite
Ivar = numpy.array([])
Ivectors = Matrix(numpy.zeros((0, vectors.shape[1])))
if infinite.any():
#square up the infinite vectors
#Ivar is unused
(Ivar, Ivectors) = _subSquare(
vectors = vectors[infinite, :],
var = numpy.ones_like(var[infinite]),
full = True
)
#take the finite variances and vectors
var = var[~infinite]
vectors = vectors[~infinite, :]
small = helpers.approx(Ivar)
Ivar = Ivar[~small]
SIvectors = Ivectors[~small, :]
if vectors.any():
#revove the component parallel to each infinite vector
vectors = vectors-vectors*SIvectors.H*SIvectors
elif var.size :
num = helpers.approx(var).sum()
#gab the extra vectors here, because if the vectors are all zeros eig will fail
vectors = Ivectors[small, :]
vectors = vectors[:num, :]
Ivectors = SIvectors
if var.size:
(var, vectors) = _subSquare(vectors, var)
if Ivar.size and var.size:
#sort the finite variances
order = numpy.argsort(abs(var))
var = var[order]
vectors = vectors[order, :]
#if there are more vectors than dimensions
kill = var.size + Ivar.size - vectors.shape[1]
if kill>0:
#squeeze the vectors with the smallest variances
var = var[kill:]
vectors = vectors[kill:, :]
return (
numpy.concatenate((var, numpy.inf*numpy.ones_like(Ivar))),
numpy.vstack([vectors, Ivectors])
)
def square(vectors, var=None, full=False):
"""
calculates the eigen-vectors and eigen-values of the covariance matrix that
would be produced by multiplying out A.var*numpy.array(A.vectors.H)*A.vectors
without necessarily calculating the covariance matrix itself.
It is also setup to handle vectors with infinite variances.
origionally the idea came from these two line on wikipedia:
http://en.wikipedia.org/wiki/Square_root_of_a_matrix:
'''if T = A*A.H = B*B.H, then there exists a unitary U s.t. A = B*U'''
http://en.wikipedia.org/wiki/Unitary_matrix
'''In mathematics, a unitary matrix is an nxn complex matrix U satisfying
the condition U.H*U = I, U*U.H = I'''
*********************************
A better description for all this is the compact singular value decomposition.
http://en.wikipedia.org/wiki/Singular_value_decomposition#Compact_SVD
but here I only need one of the two sets of vectors, so I actually calculate the smaller of
the two possible covariance marixes and, and then it's eigen-stuff.
"""
if var is None:
var = numpy.ones(vectors.shape[0])
finite = numpy.isfinite(var) & numpy.isfinite(vectors.asarray()).all(1)
infinite = ~finite
Ivar = numpy.array([])
Ivectors = Matrix(numpy.zeros((0, vectors.shape[1])))
if infinite.any():
#square up the infinite vectors
#Ivar is unused
(Ivar, Ivectors) = _subSquare(vectors=vectors[infinite, :],
var=numpy.ones_like(var[infinite]),
full=True)
#take the finite variances and vectors
var = var[~infinite]
vectors = vectors[~infinite, :]
small = helpers.approx(Ivar)
Ivar = Ivar[~small]
SIvectors = Ivectors[~small, :]
if vectors.any():
#revove the component parallel to each infinite vector
vectors = vectors - vectors * SIvectors.H * SIvectors
elif var.size:
num = helpers.approx(var).sum()
#gab the extra vectors here, because if the vectors are all zeros eig will fail
vectors = Ivectors[small, :]
vectors = vectors[:num, :]
Ivectors = SIvectors
if var.size:
(var, vectors) = _subSquare(vectors, var)
if Ivar.size and var.size:
#sort the finite variances
order = numpy.argsort(abs(var))
var = var[order]
vectors = vectors[order, :]
#if there are more vectors than dimensions
kill = var.size + Ivar.size - vectors.shape[1]
if kill > 0:
#squeeze the vectors with the smallest variances
var = var[kill:]
vectors = vectors[kill:, :]
return (numpy.concatenate((var, numpy.inf * numpy.ones_like(Ivar))),
numpy.vstack([vectors, Ivectors]))
def approx(self, *args):
return helpers.approx(*args, atol = self.atol, rtol = self.rtol)
def approx(self, *args):
return helpers.approx(*args, atol=self.atol, rtol=self.rtol)
