javiche

Small package to enable using ceviche with a JAX optimizer easily.

Install

This package is not yet published. As soon as it is install with:

pip install javiche

or

conda install javiche

How to use

Import the decorator

from javiche import jaxit

decorate your function (will be differentiated using ceviches jacobian -> HIPS autograd)

@jaxit()
def square(A):
  """squares number/array"""
  return A**2

Now you can use jax as usual:

grad_fn = jax.grad(square)

grad_fn(2.0)

Array(4., dtype=float32, weak_type=True)

In this toy example that was already possible without the jaxit() decorator. However jaxit() decorated functions can contain autograd operators (but no jax operators):

import autograd.numpy as npa

def sin(A):
  """computes sin of number/array using autograds numpy"""
  return npa.sin(A)

grad_sin = jax.grad(sin)
try:
  print(grad_sin(0.0))
except Exception as e:
  print(e)

The numpy.ndarray conversion method __array__() was called on the JAX Tracer object Traced<ConcreteArray(0.0, dtype=float32, weak_type=True)>with<JVPTrace(level=2/0)> with
  primal = 0.0
  tangent = Traced<ShapedArray(float32[], weak_type=True)>with<JaxprTrace(level=1/0)> with
    pval = (ShapedArray(float32[], weak_type=True), None)
    recipe = LambdaBinding()
See https://jax.readthedocs.io/en/latest/errors.html#jax.errors.TracerArrayConversionError

@jaxit()
def cos(A):
  """computes sin of number/array using autograds numpy"""
  return npa.cos(A)

grad_cos = jax.grad(cos)
try:
  print(grad_cos(0.0))
except Exception as e:
  print(e)

-0.0

Usecase

This library is intended for use with ceviche, while running a JAX optimization stack as demonstated in the inverse design example