Use auto diff to get at jacobian of deflection angles#206
Merged
CKrawczyk merged 1 commit intofeature/jax_wrapperfrom Oct 25, 2024
Merged
Use auto diff to get at jacobian of deflection angles#206CKrawczyk merged 1 commit intofeature/jax_wrapperfrom
CKrawczyk merged 1 commit intofeature/jax_wrapperfrom
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These changes add the ability to use JAX to find the jacobian of deflection angles. To do this it first needs a version of the deflection angle function that takes in two scalars and returns a 2 element vector. From this `jax.jacfwd` is used to get the 2x2 jacobian for a single (y,x) value. This function is vectorized to take in a set of (y,x) values (of arbitrary shape) and return a (*shape, 2, 2) array of jacobian values. The final step is to pass the value from a `grid` object into this function.
rhayes777
approved these changes
Oct 25, 2024
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| if not use_jax: | ||
| return |
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Should this ever get called if jax is off?
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I don't expect it to, but figured just to be safe.
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Might be worth raising an exception instead?
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Something like:
if not use_jax:
raise AssertionError("Function should not be called unless JAX is in use")
return ...
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These changes add the ability to use JAX to find the jacobian of deflection angles. To do this it first needs a version of the deflection angle function that takes in two scalars and returns a 2 element vector. From this
jax.jacfwdis used to get the 2x2 jacobian for a single (y,x) value. This function is vectorized to take in a set of (y,x) values (of arbitrary shape) and return a (*shape, 2, 2) array of jacobian values.The final step is to pass the value from a
gridobject into this function.