[SciPy-Dev] Feature proposal: automatic branch selection for arcsin(), arccos()

Pauli Virtanen pav@iki...
Tue Mar 12 14:57:17 CDT 2013

12.03.2013 20:56, Nathaniel Smith kirjoitti:
> How arccos_continuous(x) different from unwrap(arccos(x))? I assume
> arccos_continuous() uses a similar heuristic to unwrap() to select
> branches?

If you plot arccos(cos(x)), you get a sawtooth instead of
discontinuities, so unwrap() doesn't help. The unwrapping needs to
consider slope discontinuities somehow, I think. This then probably
entails assumptions about the input data...

Pauli Virtanen

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