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This commit is contained in:
Wassim KABALAN 2024-10-22 12:57:34 -04:00
parent 86233081e2
commit 82b8f563a0
4 changed files with 60 additions and 44 deletions
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jaxpm/pm.py
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@ -9,8 +9,8 @@ from jaxpm.distributed import (autoshmap, fft3d, get_local_shape, ifft3d,
normal_field)
from jaxpm.growth import (dGf2a, dGfa, growth_factor, growth_factor_second,
growth_rate, growth_rate_second)
from jaxpm.kernels import (PGD_kernel, fftk, gradient_kernel, invlaplace_kernel,
longrange_kernel)
from jaxpm.kernels import (PGD_kernel, fftk, gradient_kernel,
invlaplace_kernel, longrange_kernel)
from jaxpm.painting import cic_paint, cic_paint_dx, cic_read, cic_read_dx
@ -38,8 +38,8 @@ def pm_forces(positions,
kvec = fftk(delta_k)
# Computes gravitational potential
pot_k = delta_k * invlaplace_kernel(kvec) * longrange_kernel(kvec,
r_split=r_split)
pot_k = delta_k * invlaplace_kernel(kvec) * longrange_kernel(
kvec, r_split=r_split)
# Computes gravitational forces
forces = jnp.stack([
cic_read_dx(ifft3d(-gradient_kernel(kvec, i) * pot_k),
@ -96,11 +96,15 @@ def lpt(cosmo, initial_conditions, a, halo_size=0, sharding=None,order=1):
for j in range(i + 1, 3):
# Substract squared strict-up-triangle terms
# delta2 -= jnp.fft.irfftn(- ki * kj * pot_k)**2
nabla_i_nabla_j = gradient_kernel(kvec, i) * gradient_kernel(kvec, j)
nabla_i_nabla_j = gradient_kernel(kvec, i) * gradient_kernel(
kvec, j)
delta2 -= jnp.fft.irfftn(nabla_i_nabla_j * pot_k)**2
delta_k2 = fft3d(delta2)
init_force2 = pm_forces(displacement, delta=delta_k2,halo_size=halo_size,sharding=sharding)
init_force2 = pm_forces(displacement,
delta=delta_k2,
halo_size=halo_size,
sharding=sharding)
# NOTE: growth_factor_second is renormalized: - D2 = 3/7 * growth_factor_second
dx2 = 3 / 7 * growth_factor_second(cosmo, a) * init_force2
p2 = a**2 * growth_rate_second(cosmo, a) * E * dx2
@ -153,6 +157,7 @@ def make_ode_fn(mesh_shape, halo_size=0, sharding=None):
return nbody_ode
def get_ode_fn(cosmo, mesh_shape, halo_size=0, sharding=None):
def nbody_ode(a, state, args):
@ -162,7 +167,9 @@ def get_ode_fn(cosmo, mesh_shape, halo_size=0, sharding=None):
Compatible with [Diffrax API](https://docs.kidger.site/diffrax/)
"""
pos, vel = state
forces = pm_forces(pos, mesh_shape, halo_size=halo_size, sharding=sharding) * 1.5 * cosmo.Omega_m
forces = pm_forces(
pos, mesh_shape, halo_size=halo_size,
sharding=sharding) * 1.5 * cosmo.Omega_m
# Computes the update of position (drift)
dpos = 1. / (a**3 * jnp.sqrt(jc.background.Esqr(cosmo, a))) * vel
@ -192,8 +199,11 @@ def pgd_correction(pos, mesh_shape, params):
pot_k_pgd = (delta_k * invlaplace_kernel(kvec)) * PGD_range
forces_pgd= jnp.stack([cic_read(jnp.fft.irfftn(- gradient_kernel(kvec, i)*pot_k_pgd), pos)
for i in range(3)],axis=-1)
forces_pgd = jnp.stack([
cic_read(jnp.fft.irfftn(-gradient_kernel(kvec, i) * pot_k_pgd), pos)
for i in range(3)
],
axis=-1)
dpos_pgd = forces_pgd * alpha
@ -201,6 +211,7 @@ def pgd_correction(pos, mesh_shape, params):
def make_neural_ode_fn(model, mesh_shape):
def neural_nbody_ode(state, a, cosmo: Cosmology, params):
"""
state is a tuple (position, velocities)
@ -213,15 +224,19 @@ def make_neural_ode_fn(model, mesh_shape):
delta_k = jnp.fft.rfftn(delta)
# Computes gravitational potential
pot_k = delta_k * invlaplace_kernel(kvec) * longrange_kernel(kvec, r_split=0)
pot_k = delta_k * invlaplace_kernel(kvec) * longrange_kernel(kvec,
r_split=0)
# Apply a correction filter
kk = jnp.sqrt(sum((ki / jnp.pi)**2 for ki in kvec))
pot_k = pot_k * (1. + model.apply(params, kk, jnp.atleast_1d(a)))
# Computes gravitational forces
forces = jnp.stack([cic_read(jnp.fft.irfftn(- gradient_kernel(kvec, i)*pot_k), pos)
for i in range(3)],axis=-1)
forces = jnp.stack([
cic_read(jnp.fft.irfftn(-gradient_kernel(kvec, i) * pot_k), pos)
for i in range(3)
],
axis=-1)
forces = forces * 1.5 * cosmo.Omega_m
@ -232,4 +247,5 @@ def make_neural_ode_fn(model, mesh_shape):
dvel = 1. / (a**2 * jnp.sqrt(jc.background.Esqr(cosmo, a))) * forces
return dpos, dvel
return neural_nbody_ode