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Tangent: Source-To-Source Autodiff for Python

• simonbyrne 9y ago
  No nested differentiation: >>> import tangent >>> import numpy as np >>> tangent.grad(tangent.grad(np.sin)) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/lib/python3.6/site-packages/tangent/grad_util.py", line 178, in grad node, namespace = grad_tree(func, wrt, motion, mode, preserve_result, verbose) File "/usr/local/lib/python3.6/site-packages/tangent/grad_util.py", line 97, in grad_tree namespace.update(six.get_function_globals(func)) AttributeError: 'numpy.ufunc' object has no attribute '__globals__'
  • dbieber 9y ago
    ^I get that error with just `tangent.grad(np.sin)`. So, it's not a nested differentiation problem, so much as a problem with "ufuncs". If you wrap np.sin in your own function then it takes the gradient just fine. def sin(x): return np.sin(x) negative_sin = tangent.grad(tangent.grad(sin))
    • simonbyrne 9y ago
      Ah, good point, thanks!