[SciPy-dev] nbinom.ppf

Robert Kern robert.kern@gmail....
Tue Jul 28 11:56:41 CDT 2009

On Mon, Jul 27, 2009 at 20:11, <josef.pktd@gmail.com> wrote:
> That's better. It took me a while to understand the logic behind the
> way the ceiling error is corrected. The same pattern is also followed
> by the other discrete distributions that define a _ppf method. It is
> cleaner then the epsilon correction, but takes longer to figure out
> what it does.
> To understand the logic more easily and to be DRY, it would be better
> to replace the duplication of the _cdf method directly with a call to
> self._cdf.
> For example, in changeset 4673, Robert, you changed the _cdf method to
> use betainc instead of nbdtr, but not the _ppf method. Without the
> code duplication, partial corrections could be more easily avoided.
> Is there a reason not to call self._cdf instead?

Nope. Go ahead.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco

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