The recent correspondence under the former heading
appears to demonstrate a problem with u//. for
non-commutative u . The value delivered is the same
as u~//.
eg (with extra line throws in case some are ignored)
tab NB. 2 row matrix
100.978 100.368 100.663 100.874
100.971 100.047 100.33 100.013
</.tab NB. the boxed arguments for oblique
+-------+---------------+---------------+--------------+-------+
|100.978|100.368 100.971|100.663 100.047|100.874 100.33|100.013|
+-------+---------------+---------------+--------------+-------+
-//.tab NB. try subtract
100.978 0.603614 _0.615946 _0.54397 100.013
-~//.tab
100.978 0.603614 _0.615946 _0.54397 100.013
-/ each </. tab NB. correct result?!
+-------+---------+--------+-------+-------+
|100.978|_0.603614|0.615946|0.54397|100.013|
+-------+---------+--------+-------+-------+
%//.tab NB. try divide
100.978 1.00601 0.993881 0.994607 100.013
%~//.tab
100.978 1.00601 0.993881 0.994607 100.013
!//.tab NB. try "out of"
100.978 0.0275227 19.149 13.8644 100.013
!~//.tab
100.978 0.0275227 19.149 13.8644 100.013
Two devices at least get round the problem,
but with considerable loss of elegance:
!`!//.tab NB. Raul (I think)
100.978 18.1541 0.0252168 0.041804 100.013
!/@:,/.tab NB. Mike
100.978 18.1541 0.0252168 0.041804 100.013
David Alis's note (below) suggests that
user-defined verbs are safe.
Mike
david alis wrote:
On 6/7/07, Mike Day <mike_liz.day at tiscali.co.uk> wrote:
Why doesn't " ~ " work here? Is this a bug or one of
those features I keep missing?
However,
q=.%/
4{.open (q/.@:,:)close
100.617 0.996043 1.00659 1.00291 NB. ok
4{.open (%//.@:,:)close
100.617 1.00397 0.993454 0.997096 NB. not ok
Furthermore:
s=.(q/.@:,:)
4{.open (s f.) close
100.617 1.00397 0.993454 0.997096
4{.open (s ) close
100.617 0.996043 1.00659 1.00291
where:
4{."1 open,:close
100.617 100.572 100.706 100.622
100.971 100.047 100.33 100.013
Strange that this behaviour wasn't noticed before.
What else is would affected by whatever is causing this?
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