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import functools | ||
from functools import partial | ||
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import jax | ||
from jax import tree_util | ||
from jax.core import Primitive | ||
from jax.interpreters import ad | ||
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__all__ = [ | ||
'defjvp', | ||
'defjvp', | ||
] | ||
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def defjvp(primitive, *jvp_rules): | ||
"""Define JVP rules for any JAX primitive. | ||
"""Define JVP rules for any JAX primitive. | ||
This function is similar to ``jax.interpreters.ad.defjvp``. | ||
However, the JAX one only supports primitive with ``multiple_results=False``. | ||
``brainpy.math.defjvp`` enables to define the independent JVP rule for | ||
each input parameter no matter ``multiple_results=False/True``. | ||
This function is similar to ``jax.interpreters.ad.defjvp``. | ||
However, the JAX one only supports primitive with ``multiple_results=False``. | ||
``brainpy.math.defjvp`` enables to define the independent JVP rule for | ||
each input parameter no matter ``multiple_results=False/True``. | ||
For examples, please see ``test_ad_support.py``. | ||
For examples, please see ``test_ad_support.py``. | ||
Args: | ||
primitive: Primitive, XLACustomOp. | ||
*jvp_rules: The JVP translation rule for each primal. | ||
""" | ||
assert isinstance(primitive, Primitive) | ||
if primitive.multiple_results: | ||
ad.primitive_jvps[primitive] = partial(_standard_jvp, jvp_rules, primitive) | ||
else: | ||
ad.primitive_jvps[primitive] = partial(ad.standard_jvp, jvp_rules, primitive) | ||
Args: | ||
primitive: Primitive, XLACustomOp. | ||
*jvp_rules: The JVP translation rule for each primal. | ||
""" | ||
assert isinstance(primitive, Primitive) | ||
if primitive.multiple_results: | ||
ad.primitive_jvps[primitive] = partial(_standard_jvp, jvp_rules, primitive) | ||
else: | ||
ad.primitive_jvps[primitive] = partial(ad.standard_jvp, jvp_rules, primitive) | ||
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def _standard_jvp(jvp_rules, primitive: Primitive, primals, tangents, **params): | ||
assert primitive.multiple_results | ||
val_out = tuple(primitive.bind(*primals, **params)) | ||
tree = tree_util.tree_structure(val_out) | ||
tangents_out = [] | ||
for rule, t in zip(jvp_rules, tangents): | ||
if rule is not None and type(t) is not ad.Zero: | ||
r = tuple(rule(t, *primals, **params)) | ||
tangents_out.append(r) | ||
assert tree_util.tree_structure(r) == tree | ||
return val_out, functools.reduce(_add_tangents, | ||
tangents_out, | ||
tree_util.tree_map(lambda a: ad.Zero.from_value(a), val_out)) | ||
assert primitive.multiple_results | ||
val_out = tuple(primitive.bind(*primals, **params)) | ||
tree = tree_util.tree_structure(val_out) | ||
tangents_out = [] | ||
for rule, t in zip(jvp_rules, tangents): | ||
if rule is not None and type(t) is not ad.Zero: | ||
r = tuple(rule(t, *primals, **params)) | ||
tangents_out.append(r) | ||
assert tree_util.tree_structure(r) == tree | ||
return val_out, functools.reduce( | ||
_add_tangents, | ||
tangents_out, | ||
tree_util.tree_map( | ||
# compatible with JAX 0.4.34 | ||
lambda a: ad.Zero.from_primal_value(a) if jax.__version__ >= '0.4.34' else ad.Zero.from_value(a), | ||
val_out | ||
) | ||
) | ||
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def _add_tangents(xs, ys): | ||
return tree_util.tree_map(ad.add_tangents, xs, ys, is_leaf=lambda a: isinstance(a, ad.Zero)) | ||
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return tree_util.tree_map(ad.add_tangents, xs, ys, is_leaf=lambda a: isinstance(a, ad.Zero)) |