Thanks, looks good.
Nice to see reusable code like 'trivial' and interesting case-select
code with an adverb selector like:
> reduceStep=: reduce0`reduce1`]@.(2<. {.@{.) NonTrivial
Small step, RREF with less characters:
RREF =: {.&>@ (reduceStep@}.&.>^:(1<#&>)^:a:@<@reduceStep)&.|. @ REF
I agree with your final note.
*./0={.y
handles both
i.0 and i.0 0
In Haskell you need the first pattern
rowEchelonForm [] = []
to handle []
The final pattern
rowEchelonForm zs@([]:_) = zs
handles
[[]]
If you leave out the first pattern, you get with a stupid argument like []
> rowEchelonForm []
*** Exception: /rref.hs:(62,1)-(69,29): Non-exhaustive patterns in function
rowEchelonForm
On 22-04-12 20:16, Raul Miller wrote:
> Here's an attempt at making this code more "J-ish". Mostly, I have
> been assigning names to blocks (instead of allowing anonymous blocks).
>
> I need better names, though. ref0N is not a very evocative name.
>
>
> trivial=: 0 *./ .= {.
> NonTrivial=: ^:(0 = trivial)
>
> refN=: (], 0,. [:REF 1 1}. [ - {."1@[ */ ]) (%{.)@{.
> ref00=: 0,. [:REF }."1
> ref0N=: [:REF (}.,~ {. + ({.@#~ 0 ~: {."1))
> ref0=: ref0N`ref00@.(trivial@:|:)
> REF=: refN`ref0@.(0 = {.@{.)NonTrivial
>
> reduce0=: {."1,. [: reduceStep }."1
> reduce1=: {., 0 ,. }."1@}.@(- ({."1 */ {.))
> reduceStep=: reduce0`reduce1`]@.(2<. {.@{.) NonTrivial
>
> RREF =: ([:{.&> (reduceStep@}.&.>^:(1<#&>)^:a:@<@reduceStep))&.|. @ REF
>
> Note that I have eliminated the code corresponding to
>
> if. 0=#y do. i.0 0 return. end.
>
> since this case never happens -- it is handled by
>
> if. *./0={.y do. y return. end.
>
> FYI,
>
--
Met vriendelijke groet,
@@i = Arie Groeneveld
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