[Numpy-discussion] add xirr to numpy financial functions?

Matt Knox mattknox.ca@gmail....
Mon May 25 20:18:25 CDT 2009

forgive me for jumping in on this thread and playing devil's advocate here, but
I am a natural pessimist so please bear with me :) ...

I think as this discussion has already demonstrated, it is *extremely*
difficult to build a solid general purpose API for financial functions (even
seemingly simple ones like an IRR calculation) because of the endless amount
of possible permutations and interpretations. I think it would be a big
mistake to add more financial functions to numpy directly without having them
mature independently in a separate (scikits) package first. It is virtually
guaranteed that you won't get the API right on the first try and adding the
functions to numpy locks you into an API commitment because numpy is supposed
to be a stable package with certain guarantees for backwards compatibility.

And as for a more fully featured finance/quant module in Python... someone has
already mentioned the C++ library, QuantLib - which I use extensively at work
- and I think any serious effort to improve Python's capabilities in this area
would be best spent on building a good Python/numpy interface to QuantLib
rather than reimplementing its very substantial functionality (which is
probably an impossible task realistically).

- Matt

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