Re: Proposal: Add log1p and expm1 to GHC.Float.Floating

On 2014-04-17 15:08, Edward Kmett wrote:

On Thu, Apr 17, 2014 at 2:48 PM, Henning Thielemann mailto:schlepptop@henning-thielemann.de> wrote:

I think one should add default implementations. They don't have an numerical advantage but they save programmers from code breakage.

I included the default definitions in code snippet in the proposal, so user code that remains unaware of them would be unaffected, while packages like compensated, or a wrapper around libqd could implement them as needed.

expm1 :: Floating a => a -> a expm1 x = exp x - 1

log1p :: Floating a => a -> a log1p x = log (1 + x) On the contrary, code that explicitly uses these functions is likely to need the precision. Defaults would cause subtle breakage.

-- Scott