def SL0_approx_dai(A,
x,
eps,
sigma_min,
sigma_decrease_factor=0.5,
mu_0=2,
L=3,
A_pinv=None,
true_s=None):
if A_pinv is None:
A_pinv = numpy.linalg.pinv(A)
if true_s is not None:
ShowProgress = True
else:
ShowProgress = False
# Initialization
#s = A\x;
s = numpy.dot(A_pinv, x)
sigma = 2.0 * numpy.abs(s).max()
# Main Loop
while sigma > sigma_min:
for i in numpy.arange(L):
delta = OurDelta(s, sigma)
s = s - mu_0 * delta
# At this point, s no longer exactly satisfies x = A*s
# The original SL0 algorithm projects s onto {s | x = As} with
# s = s - numpy.dot(A_pinv,(numpy.dot(A,s)-x)) # Projection
# We want to project s onto {s | |x-As| < eps}
# We move onto the direction -A_pinv*(A*s-x), but only with a
# smaller step:
direction = numpy.dot(A_pinv, (numpy.dot(A, s) - x))
if (numpy.linalg.norm(numpy.dot(A, direction)) >= eps):
#s = s - (1.0 - eps/numpy.linalg.norm(numpy.dot(A,direction))) * direction
try:
s = EllipseProj.ellipse_proj_dai(A, x, s, eps)
except Exception, e:
#raise EllipseProj.EllipseProjDaiError(e)
raise EllipseProj.EllipseProjDaiError()
#assert(numpy.linalg.norm(x - numpy.dot(A,s)) < eps + 1e-6)
if ShowProgress:
#fprintf(' sigma=#f, SNR=#f\n',sigma,estimate_SNR(s,true_s))
string = ' sigma=%f, SNR=%f\n' % sigma, estimate_SNR(s, true_s)
print string
sigma = sigma * sigma_decrease_factor
def SL0_approx_analysis_dai(Aeps,
Aexact,
x,
eps,
sigma_min,
sigma_decrease_factor=0.5,
mu_0=2,
L=3,
Aeps_pinv=None,
Aexact_pinv=None,
true_s=None):
if Aeps_pinv is None:
Aeps_pinv = numpy.linalg.pinv(Aeps)
if Aexact_pinv is None:
Aexact_pinv = numpy.linalg.pinv(Aexact)
if true_s is not None:
ShowProgress = True
else:
ShowProgress = False
# Initialization
#s = A\x;
s = numpy.dot(Aeps_pinv, x)
sigma = 2.0 * numpy.abs(s).max()
# Main Loop
while sigma > sigma_min:
for i in numpy.arange(L):
delta = OurDelta(s, sigma)
s = s - mu_0 * delta
# At this point, s no longer exactly satisfies x = A*s
# The original SL0 algorithm projects s onto {s | x = As} with
# s = s - numpy.dot(A_pinv,(numpy.dot(A,s)-x)) # Projection
#
# We want to project s onto {s | |x-AEPS*s|<eps AND |Aexact*s|=0}
# First: make s orthogonal to Aexact (|Aexact*s|=0)
# Second: move onto the direction -A_pinv*(A*s-x), but only with a smaller step:
# This separation assumes that the rows of Aexact are orthogonal to the rows of Aeps
#
# 1. Make s orthogonal to Aexact:
# s = s - Aexact_pinv * Aexact * s
s = s - numpy.dot(Aexact_pinv, (numpy.dot(Aexact, s)))
# 2. Move onto the direction -A_pinv*(A*s-x), but only with a smaller step:
direction = numpy.dot(Aeps_pinv, (numpy.dot(Aeps, s) - x))
# Nic 10.04.2012: Why numpy.dot(Aeps,direction) and not just 'direction'?
# Nic 10.04.2012: because 'direction' is of size(s), but I'm interested in it's projection on Aeps
if (numpy.linalg.norm(numpy.dot(Aeps, direction)) >= eps):
# s = s - (1.0 - eps/numpy.linalg.norm(numpy.dot(Aeps,direction))) * direction
try:
s = EllipseProj.ellipse_proj_dai(Aeps, x, s, eps)
except Exception, e:
#raise EllipseProj.EllipseProjDaiError(e)
raise EllipseProj.EllipseProjDaiError()
#assert(numpy.linalg.norm(x - numpy.dot(A,s)) < eps + 1e-6)
if ShowProgress:
#fprintf(' sigma=#f, SNR=#f\n',sigma,estimate_SNR(s,true_s))
string = ' sigma=%f, SNR=%f\n' % sigma, estimate_SNR(s, true_s)
print string
sigma = sigma * sigma_decrease_factor
