[Haskell-cafe] convergence of functions of Complex variables
iakd0 at clusterf.urz.uni-halle.de
Wed Dec 15 06:41:39 EST 2004
On Wed, 15 Dec 2004, William Lee Irwin III wrote:
> On Wed, Dec 15, 2004 at 10:28:18AM +0000, Ross Paterson wrote:
> > abs :: Num a => a -> a, whereas you want something that returns a Double.
> > You could define
> > class Norm a where
> > norm :: a -> Double
> > instance Norm Float where
> > norm = realToFrac . abs
> > instance Norm Double where
> > norm = abs
> > instance RealFloat a => Norm (Complex a) where
> > norm = realToFrac . magnitude
> > and use norm instead of abs.
> Thanks; this appears to do the trick for me. Something of this kind
> would be useful to have in the std. libraries, at least for me.
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