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Merge remote-tracking branch 'upstream/main' into ASKabalan/jaxdecomp_proto

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This commit is contained in:
Wassim KABALAN 2024-10-22 12:59:50 -04:00
commit 85cca44fb0
2 changed files with 21 additions and 4 deletions
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21
jaxpm/pm.py
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@ -157,6 +157,27 @@ def make_ode_fn(mesh_shape, halo_size=0, sharding=None):
return nbody_ode
def get_ode_fn(cosmo:Cosmology, mesh_shape):
def nbody_ode(a, state, args):
"""
State is an array [position, velocities]
Compatible with [Diffrax API](https://docs.kidger.site/diffrax/)
"""
pos, vel = state
forces = pm_forces(pos, mesh_shape) * 1.5 * cosmo.Omega_m
# Computes the update of position (drift)
dpos = 1. / (a**3 * jnp.sqrt(jc.background.Esqr(cosmo, a))) * vel
# Computes the update of velocity (kick)
dvel = 1. / (a**2 * jnp.sqrt(jc.background.Esqr(cosmo, a))) * forces
return jnp.stack([dpos, dvel])
return nbody_ode
def get_ode_fn(cosmo, mesh_shape, halo_size=0, sharding=None):