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Update solver.py #1

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20 changes: 11 additions & 9 deletions mlat/solver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@

from mlat import geodesy, constants, profile
from mlat import config
import numpy as np

# The core of it all. Not very big, is it?
# (Admittedly the entire least-squares solver is hidden within scipy..)
Expand All @@ -36,7 +37,7 @@


def _residuals(x_guess, pseudorange_data, altitude, altitude_error):
"""Return an array of residuals for a position guess at x_guess versus
"""Return the sum of squared residuals for a position guess at x_guess versus
actual measurements pseudorange_data and altitude."""

(*position_guess, offset) = x_guess
Expand All @@ -53,7 +54,8 @@ def _residuals(x_guess, pseudorange_data, altitude, altitude_error):
_, _, altitude_guess = geodesy.ecef2llh(position_guess)
res.append((altitude - altitude_guess) / altitude_error)

return res
# return the sum of squared residuals
return np.sum(np.array(res)**2)


@profile.trackcpu
Expand Down Expand Up @@ -91,19 +93,19 @@ def solve(measurements, altitude, altitude_error, initial_guess):
math.sqrt(variance) * constants.Cair)
for receiver, timestamp, variance in measurements]
x_guess = [initial_guess[0], initial_guess[1], initial_guess[2], 0.0]
x_est, cov_x, infodict, mesg, ler = scipy.optimize.leastsq(
res = scipy.optimize.minimize(
_residuals,
x_guess,
args=(pseudorange_data, altitude, altitude_error),
full_output=True,
maxfev=config.SOLVER_MAXFEV)
method='BFGS',
options={'maxiter': config.SOLVER_MAXFEV})

if ler in (1, 2, 3, 4):
if res.success:
#glogger.info("solver success: {0} {1}".format(ler, mesg))

# Solver found a result. Validate that it makes
# some sort of physical sense.
(*position_est, offset_est) = x_est
(*position_est, offset_est) = res.x

if offset_est < 0 or offset_est > 500e3:
#glogger.info("solver: bad offset: {0}".formaT(offset_est))
Expand All @@ -118,10 +120,10 @@ def solve(measurements, altitude, altitude_error, initial_guess):
# #glogger.info("solver: bad range: {0}".format(d))
# return None

if cov_x is None:
if res.hess_inv is None:
return position_est, None
else:
return position_est, cov_x[0:3, 0:3]
return position_est, res.hess_inv[0:3, 0:3]

else:
# Solver failed
Expand Down