[Bug-apl] Outer product problems

[Darek Cidlinsky]

Ave,
        I have two problems with outer product in GNU APL; one of them is maybe 
a bug, the other is nearly definitely a bug.

        If I use the product with a standard function like ×, everything works 
as it should:

              ∘.×/ (5 2) (7 6 4)
         35 30 20 
         14 12  8 
        
        However, if I replace it with a custom function, it does something 
different:

              ∘.{⍺×⍵}/ (5 2) (7 6 4)
        35

        It does the exactly same thing with custom non-lambda functions

              P ← {⍺×⍵}
              ∘.P/ (5 2) (7 6 4)
        35


        I have only little experience with APL (30 hours), but I think that all 
functions are created equal (I hope so!), and the both products above should be 
same. (If it's a valid behaviour, -- a feature, not a bug -- I'd be grateful if 
you could explain it to me.)

        [ If I envelope the whole product in a lambda, it works again:

              {⍺ ∘.{⍺×⍵} ⍵}/ (5 2) (7 6 4)
         35 30 20 
         14 12  8 
        
        ]

        Now for the sure bug: the expression (for two bit vectors K and L -- it 
doesn't seem to depend on their contents or shapes)

        K { { ⍺ ∘.{| ⍺ - ⍵ + 0J1} ⍵}/ {⍵/⍳⍴⍵}¨⍺ ⍵} L

        was supposed to get the positions of 1s in both vectors ( {⍵/⍳⍴⍵}¨⍺ ⍵ , 
and do an outer product of these position lists using a function " 
sqrt(difference^2 + 1) ". However, it says 

        copying:             '0' at Executable.cc:627
        tidx:                '2' at Executable.cc:628

        ----------------------------------------
        -- Stack trace at Executable.cc:629
        ----------------------------------------
        0x7f8af60cfb45 __libc_start_main
        0x43b425  main
        0x53909d   Workspace::immediate_execution(bool)
        0x474365    Command::process_line()
        0x46e1d0     Command::do_APL_expression(UCS_string&)
        0x4811c4      StatementList::fix(UCS_string const&, char const*)
        0x480030       Executable::setup_lambdas()
        0x5290af        UserFunction::UserFunction(Fun_signature, UCS_string 
const&, UCS_string const&, Token_string const&)
        0x480030         Executable::setup_lambdas()
        0x5290af          UserFunction::UserFunction(Fun_signature, UCS_string 
const&, UCS_string const&, Token_string const&)
        0x47fffe           Executable::setup_lambdas()
        0x47ec2f            Executable::extract_lambda_text(Fun_signature, int) 
const
        ========================================

        and exits (with state of 0). I think it shouldn't do that.

        [ But if I omit the {⍵/⍳⍴⍵}¨⍺ ⍵ and give some vector literals instead, 
it works as intended:

              {⍺∘.{|⍺-⍵+0J1}⍵}/ (5 2) (7 6 4)
         2.236067977 1.414213562 1.414213562 
         5.099019514 4.123105626 2.236067977 
        ]

Optime vale,
        D.

P. S.: This behaviour is exhibited by the Debian package (apl_1.4-1_amd64.deb) 
as well as by the source in Svn repository.
P. P. S.: I switched on all 41 logging facilites and ran it again. The 
resulting log should be attached.

outer-product-crash.log
Description: Text document