forked from guilhem_lavaux/JaxPM
100 lines
3.4 KiB
Python
100 lines
3.4 KiB
Python
import jax
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import jax.lax as lax
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import jax.numpy as jnp
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from jaxpm.kernels import cic_compensation, fftk
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def cic_paint(mesh, positions, weight=None):
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""" Paints positions onto mesh
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mesh: [nx, ny, nz]
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positions: [npart, 3]
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"""
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positions = jnp.expand_dims(positions, 1)
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floor = jnp.floor(positions)
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connection = jnp.array([[[0, 0, 0], [1., 0, 0], [0., 1, 0], [0., 0, 1],
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[1., 1, 0], [1., 0, 1], [0., 1, 1], [1., 1, 1]]])
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neighboor_coords = floor + connection
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kernel = 1. - jnp.abs(positions - neighboor_coords)
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kernel = kernel[..., 0] * kernel[..., 1] * kernel[..., 2]
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if weight is not None:
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kernel = jnp.multiply(jnp.expand_dims(weight, axis=-1), kernel)
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neighboor_coords = jnp.mod(
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neighboor_coords.reshape([-1, 8, 3]).astype('int32'),
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jnp.array(mesh.shape))
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dnums = jax.lax.ScatterDimensionNumbers(update_window_dims=(),
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inserted_window_dims=(0, 1, 2),
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scatter_dims_to_operand_dims=(0, 1,
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2))
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mesh = lax.scatter_add(mesh, neighboor_coords, kernel.reshape([-1, 8]),
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dnums)
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return mesh
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def cic_read(mesh, positions):
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""" Paints positions onto mesh
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mesh: [nx, ny, nz]
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positions: [npart, 3]
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"""
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positions = jnp.expand_dims(positions, 1)
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floor = jnp.floor(positions)
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connection = jnp.array([[[0, 0, 0], [1., 0, 0], [0., 1, 0], [0., 0, 1],
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[1., 1, 0], [1., 0, 1], [0., 1, 1], [1., 1, 1]]])
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neighboor_coords = floor + connection
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kernel = 1. - jnp.abs(positions - neighboor_coords)
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kernel = kernel[..., 0] * kernel[..., 1] * kernel[..., 2]
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neighboor_coords = jnp.mod(neighboor_coords.astype('int32'),
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jnp.array(mesh.shape))
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return (mesh[neighboor_coords[..., 0], neighboor_coords[..., 1],
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neighboor_coords[..., 3]] * kernel).sum(axis=-1)
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def cic_paint_2d(mesh, positions, weight):
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""" Paints positions onto a 2d mesh
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mesh: [nx, ny]
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positions: [npart, 2]
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weight: [npart]
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"""
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positions = jnp.expand_dims(positions, 1)
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floor = jnp.floor(positions)
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connection = jnp.array([[0, 0], [1., 0], [0., 1], [1., 1]])
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neighboor_coords = floor + connection
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kernel = 1. - jnp.abs(positions - neighboor_coords)
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kernel = kernel[..., 0] * kernel[..., 1]
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if weight is not None:
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kernel = kernel * weight[..., jnp.newaxis]
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neighboor_coords = jnp.mod(
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neighboor_coords.reshape([-1, 4, 2]).astype('int32'),
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jnp.array(mesh.shape))
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dnums = jax.lax.ScatterDimensionNumbers(update_window_dims=(),
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inserted_window_dims=(0, 1),
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scatter_dims_to_operand_dims=(0,
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1))
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mesh = lax.scatter_add(mesh, neighboor_coords, kernel.reshape([-1, 4]),
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dnums)
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return mesh
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def compensate_cic(field):
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"""
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Compensate for CiC painting
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Args:
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field: input 3D cic-painted field
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Returns:
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compensated_field
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"""
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nc = field.shape
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kvec = fftk(nc)
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delta_k = jnp.fft.rfftn(field)
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delta_k = cic_compensation(kvec) * delta_k
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return jnp.fft.irfftn(delta_k)
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