odisseo.initial_condition module

odisseo.initial_condition.Plummer_sphere(key: Key[Array, ''] | UInt32[Array, '2'], config: SimulationConfig, params: SimulationParams) → tuple

Create initial conditions for a Plummer sphere. The sampling of velocities is done by inverse fitting the cumulative distribution function of the Plummer sphere.

Parameters:

• key (jax.random.PRNGKey) – Random key.

• config (NamedTuple) – Configuration NamedTuple containing the number of particles (N_particles).

• params (NamedTuple) – Parameters NamedTuple containing:

Returns:

tuple –

A tuple containing:

positions (jnp.array): Array of shape (N_particles, 3) representing the positions of the particles. velocities (jnp.array): Array of shape (N_particles, 3) representing the velocities of the particles. masses (jnp.array): Array of shape (N_particles,) representing the masses of the particles.

odisseo.initial_condition.Plummer_sphere_reparam(noise: Array, config: SimulationConfig, params: SimulationParams) → tuple

Reparameterized Plummer sphere generation.

Parameters:

• noise (jnp.ndarray) – Pre-sampled uniform random numbers of shape (N_particles, 6) where each column corresponds to: [0]: radial sampling [1]: position azimuthal angle [2]: position polar angle [3]: velocity magnitude sampling [4]: velocity azimuthal angle [5]: velocity polar angle

• config (SimulationConfig) – Configuration containing N_particles

• params (SimulationParams) – Parameters containing Plummer_params, G

Returns:

tuple – Same as original Plummer_sphere function

odisseo.initial_condition.ic_two_body(mass1: float | Array, mass2: float | Array, rp: float | Array, e: float | Array, params: SimulationParams) → tuple

Create initial conditions for a two-body system.

By default, the two bodies will be placed along the x-axis at the closest distance rp. Depending on the input eccentricity, the two bodies can be in a circular (e < 1), parabolic (e = 1), or hyperbolic orbit (e > 1).

Parameters:

• mass1 (float) – Mass of the first body [nbody units].

• mass2 (float) – Mass of the second body [nbody units].

• rp (float) – Closest orbital distance [nbody units].

• e (float) – Eccentricity.

• config (NamedTuple) – Configuration NamedTuple.

• params (NamedTuple) – Parameters NamedTuple.

Returns:

tuple –

A tuple containing:

• pos (jnp.ndarray): Positions of the particles.

• vel (jnp.ndarray): Velocities of the particles.

• mass (jnp.ndarray): Masses of the particles.

odisseo.initial_condition.inclined_circular_velocity(position: Array, v_c: Array, inclination: Array)

Convert circular velocity module on the xy plane to an inclined orbit Cartesian components.

Parameters:

• position (jnp.ndarray) – (x, y, z) position of the Plummer sphere.

• v_c (float) – Circular velocity (km/s).

• inclination (float) – Inclination angle in radians.

Returns:

jnp.ndarray – (v_x, v_y, v_z) velocity components.

odisseo.initial_condition.inclined_position(position: Array, inclination: Array)

Convert position on the xy-plane to an inclined orbit.

Parameters:

• position (jnp.ndarray) – (x, y, z) position of the Plummer sphere.

• inclination – Inclination angle in radians.

odisseo.initial_condition.sample_position_on_circle(key: Key[Array, ''] | UInt32[Array, '2'], r_p: float, num_samples: int = 1)

Sample uniform positions on a sphere of radius r_p.

Parameters:

• key (jax.random.PRNGKey) – JAX random key for sampling.

• r_p (float) – Radius of the sphere.

• num_samples (int) – Number of samples to generate.

Returns:

jnp.ndarray – Sampled positions (num_samples, 3).

odisseo.initial_condition.sample_position_on_sphere(key: Key[Array, ''] | UInt32[Array, '2'], r_p: float, num_samples: int = 1)

Sample uniform positions on a sphere of radius r_p.

Parameters:

• key (jax.random.PRNGKey) – JAX random key for sampling.

• r_p (float) – Radius of the sphere.

• num_samples (int) – Number of samples to generate. Deafult is 1.

Returns:

jnp.ndarray – Sampled positions (num_samples, 3).