[SciPy-user] [ANN][Automatic Differentiation] Beta Version of PYADOLC
David Warde-Farley
dwf at cs.toronto.edu
Tue May 12 16:25:21 EDT 2009
On 12-May-09, at 12:41 PM, Pauli Virtanen wrote:
> AD typically builds an "implicit" graph expression corresponding to
> the
> computation, and constructs the Jacobian based on that. So it's not
> symbolic or numerical differentiation.
I've never quite understood the difference between what AD does and
the 'symbolic' way, but from what I'm reading on Wikipedia it's just a
way of *implementing* the chain rule cleverly using graph operations.
Is that what you mean Pauli?
So it is exact differentiation (to the extent the floating point
hardware can provide) rather than an approximation such as finite
differences will yield, and thus the resulting code is equivalent in
function to what you'd get if you symbolically differentiated and then
coded it up, is that right?
Cheers,
David
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