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Hi Vivek,
It appears the python wrapper believes tolerances[0] and
tolerances[1] are of type Object instead of double[]. The python
wrapper has trouble with the Java type system and overloaded
methods in some cases. Have a look at [1]. It suggests using
JArray('double').cast_(tolerances[0]) to tell python that it is
actually a double[].
Best Regards,
Evan
[1]
https://lucene.apache.org/pylucene/jcc/features.html#handling-arrays
On 07/25/2016 06:12 PM, Vivek Vittaldev
wrote:
Hi everyone,
I am trying to use the Python Orekit wrapper to numerically
integrate orbits and I'm running into a few problems.
I am following the tutorial here:
I've gotten the Slave mode and the Ephemeris mode part of
the tutorial to work. But I get an error when I try to set up
the integrator, i.e., in the following part of the tutorial:
// Adaptive step
integrator
// with a minimum step of 0.001 and a maximum step of 1000
double minStep = 0.001;
double maxstep = 1000.0;
double positionTolerance = 10.0;
OrbitType propagationType = OrbitType.KEPLERIAN;
double[][] tolerances =
NumericalPropagator.tolerances(positionTolerance,
initialOrbit, propagationType);
AdaptiveStepsizeIntegrator integrator =
new DormandPrince853Integrator(minStep, maxstep,
tolerances[0], tolerances[1]);
The error I get is:
InvalidArgsError:
(<type 'DormandPrince853Integrator'>, '__init__',
(0.001, 1000.0, <Object: [D@e50a6f6>, <Object:
[D@14ec4505>))
It looks like it is something to do with the handling of
tolerances. I have attached my IPython notebook in case
anyone can help me. The code I have for running the example
is:
# Import all the required
libraries
#Initialize orekit and JVM
import orekit
orekit.initVM()
from orekit.pyhelpers import setup_orekit_curdir
setup_orekit_curdir()
#Apache math
from org.orekit.bodies import CelestialBodyFactory,
CelestialBody
from org.orekit.errors import OrekitException
from org.orekit.frames import LOFType, Frame, FramesFactory,
Transform
from org.orekit.orbits import KeplerianOrbit, Orbit,
CartesianOrbit, OrbitType, PositionAngle
from org.orekit.propagation import Propagator,
SpacecraftState
from org.orekit.propagation.analytical import tle,
KeplerianPropagator
from org.orekit.propagation.numerical import
NumericalPropagator, Jacobianizer, TimeDerivativesEquations
from org.orekit.time import TimeScalesFactory, AbsoluteDate,
DateComponents, TimeComponents
from org.orekit.utils import IERSConventions, Constants,
PVCoordinates, PVCoordinatesProvider
from org.orekit.python import PythonEventHandler,
PythonOrekitFixedStepHandler
from org.orekit.utils import IERSConventions
from org.hipparchus.geometry.euclidean.threed import
Vector3D
from org.hipparchus.geometry.euclidean.threed import
RotationOrder
from org.hipparchus.ode.nonstiff import
DormandPrince853Integrator, ClassicalRungeKuttaIntegrator
# Inertial frame
inertialFrame =
FramesFactory.getEME2000();
# Initial date
utc =
TimeScalesFactory.getUTC();
initialDate =
AbsoluteDate(2004, 01, 01, 23, 30, 00.000,utc);
# Central attraction
coefficient
mu = 3.986004415e+14;
# Initial orbit
a = 24396159.0;
# semi major axis in meters
e = 0.72831215;
# eccentricity
i = 0.122173; #
inclination
omega = 3.14159; #
perigee argument
raan = 4.55531; # right
ascention of ascending node
lM = 0.0;
# mean anomaly
initialOrbit =
KeplerianOrbit(a, e, i, omega, raan, lM, PositionAngle.MEAN,
inertialFrame, initialDate, mu)
# Initial state
definition
initialState =
SpacecraftState(initialOrbit);
# Adaptive step
integrator
# with a minimum step of
0.001 and a maximum step of 1000
minStep = 0.001;
maxstep = 1000.0;
positionTolerance = 10.0;
propagationType =
OrbitType.KEPLERIAN;
tolerances =
NumericalPropagator.tolerances(positionTolerance,
initialOrbit, propagationType);
integrator =
DormandPrince853Integrator(minStep,
maxstep,
tolerances[0],
tolerances[1]) # Error here
propagator =
NumericalPropagator(integrator)
propagator.setOrbitType(propagationType)
I wonder if I am missing any imports. I would greatly
appreciate any help!
Best Regards,
Vivek
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