Fix seed for distributed normal

jaxpm/distributed.py

@@ -131,3 +131,22 @@ def get_local_shape(mesh_shape):
         return [
             mesh_shape[0] // pdims[0], mesh_shape[1] // pdims[1], mesh_shape[2]
         ]
+    
+
+
+def normal_field(mesh_shape, seed=None):
+    """Generate a Gaussian random field with the given power spectrum."""
+    if distributed and not (mesh_lib.thread_resources.env.physical_mesh.empty):
+        local_mesh_shape = get_local_shape(mesh_shape)
+        if seed is None:
+            key = None
+        else:
+            size = jax.process_count()
+            rank = jax.process_index()
+            key = jax.random.split(seed, size)[rank]
+        return autoshmap(
+            partial(jax.random.normal, shape=local_mesh_shape, dtype='float32'),
+            in_specs=P(None),
+            out_specs=P('x', 'y'))(key)  # yapf: disable
+    else:
+        return jax.random.normal(shape=mesh_shape, key=seed)

jaxpm/pm.py

@@ -5,7 +5,8 @@ import jax.numpy as jnp
 import jax_cosmo as jc
 from jax.sharding import PartitionSpec as P
 
-from jaxpm.distributed import autoshmap, fft3d, get_local_shape, ifft3d
+from jaxpm.distributed import (autoshmap, fft3d, get_local_shape, ifft3d,
+                               normal_field)
 from jaxpm.growth import dGfa, growth_factor, growth_rate
 from jaxpm.kernels import (PGD_kernel, fftk, gradient_kernel, laplace_kernel,
                            longrange_kernel)
@@ -71,12 +72,7 @@ def linear_field(mesh_shape, box_size, pk, seed):
         box_size[0] * box_size[1] * box_size[2])
 
     # Initialize a random field with one slice on each gpu
-    local_mesh_shape = get_local_shape(mesh_shape)
+    field = normal_field(mesh_shape, seed=seed)
-    field = autoshmap(
-      partial(jax.random.normal, shape=local_mesh_shape, dtype='float32'),
-      in_specs=P(None),
-      out_specs=P('x', 'y'))(seed)  # yapf: disable
-
     field = fft3d(field) * pkmesh**0.5
     field = ifft3d(field)
     return field