The bit widths are calculated from the huffman tree

See

http://stackoverflow.com/questions/759707/efficient-way-of-storing-huffman-tree

http://www.siggraph.org/education/materials/HyperGraph/video/mpeg/mpegfaq/huffman_tutorial.html

The timing is interesting considering we were talking about trees the other
day:
http://jsoftware.2058.n7.nabble.com/Ragged-Array-Shapes-are-Trees-td63207.html

I was thinking to myself then how I hadn't used trees more than a few times
in 18 years of programming.

I am not sure how to apply your code to the problem.  I also am not
completely sure what problem we are solving.  If it is creating a
standalone J deflate implementation or PNG compression it may be a tall
order. I would be curious why not just interface to a C library like what
is done in the image3 addon:
http://www.jsoftware.com/jwiki/Addons/media/image3
On Sep 11, 2014 6:27 PM, "Raul Miller" <[email protected]> wrote:

> Here's the code I came up with, with Bill's help:
>
> bl_count=:3 :0 NB. y is result of freqs
>   0,}.<:#/.~(,~ [: i. 1 + >./)y
> )
>
> start_vals=: +:@+/\.&.|.@}:@,~&0
>
> find_codes=:3 :0 NB. y is result of freqs
>  b=. bl_count y
>  v=. start_vals b
>  n=. /:~ ~.y-.0
>  o=. ;({./.~ /:~ (</. i.@#)) y
>  c=. ;<"1&.>n (([#2:) #: ])&.> (*b)#v+&.>i.&.>b
>  c /: o
> )
>
> An alternate version of the result from find_codes would be given by:
>
> def_code=:3 :0
>  b=. bl_count y
>  v=. start_vals b
>  n=. /:~ ~.y-.0
>  o=. ;({./.~ /:~ (</. i.@#)) y
>  c=. ;n,.&.>(*b)#v+&.>i.&.>b
>  (,. i.@#)c /: o
> )
>
> The argument to find_codes or def_code is the bit widths for each symbol.
>
> I have not been able to figure out, from rfc 1951, how the bit widths
> are calculated.
>
> Thanks,
>
> --
> Raul
>
>
>
> On Thu, Sep 11, 2014 at 4:47 PM, Joe Bogner <[email protected]> wrote:
> > bill, I'd be interested in a solution but I don't think I can
> > contribute any more on this. I played with
> > https://code.google.com/p/miniz/ and became even more convinced of the
> > complexity. It seems as though the compressor can decide whether to
> > include the dictionary code table or not -- likely based on the size
> > of the table.
> >
> >
> > http://tools.ietf.org/html/rfc1950
> >
> > A preset dictionary is specially useful to compress short input
> >       sequences. The compressor can take advantage of the dictionary
> >       context to encode the input in a more compact manner.
> >
> >
> > More links for anyone who is following and cares to go down the rabbit
> hole too:
> >
> > http://en.wikipedia.org/wiki/Canonical_Huffman_code
> >
> >
> http://stackoverflow.com/questions/759707/efficient-way-of-storing-huffman-tree
> >
> >
> >
> > On Thu, Sep 11, 2014 at 1:28 PM, bill lam <[email protected]> wrote:
> >> This codes seemed invalid.
> >>
> >> 1 is a prefix of 11 which is a prefix of 111. Suppose there
> >> is a bit pattern of 1 1 , it is ambiguous to mean
> >> [68,'1']  [68,'1']
> >> or [65,'11']
> >>
> >> The huffman code in rfc is canonical meaning there is exactly one
> >> possible huffman codes for a given bit length vector. This is
> >> important because the huffman code table itself will not be
> >> stored inside the deflate stream. The decoder only gets the bit
> >> length vector, if encoder and decoder use different huffman code
> >> for the same bit length vectors, it will not work.
> >>
> >> Чт, 11 сен 2014, Joe Bogner написал(а):
> >>> Ignore the pako.js example output... It was just outputting the binary
> >>> representation of A-Z, not the huffman code
> >>>
> >>> This is what I meant to send
> >>>
> >>> For ABCD:
> >>>
> >>> [65,'11'],
> >>> [66,'0'],
> >>> [67,'10'],
> >>> [68,'1'],
> >>> [256,'111']
> >>>
> >>> It still doesn't seem to be sorting correctly lexographically, but I'm
> >>> not really in my comfort zone of understanding:
> >>>
> >>> The RFC has this instead:
> >>>
> >>> Symbol  Code
> >>>             ------  ----
> >>>             A       10
> >>>             B       0
> >>>             C       110
> >>>             D       111
> >>>
> >>> I don't really know if it has to match the RFC or if each
> >>> implementation is able to do its own thing as long since it includes
> >>> the distance/reverse lookup table (whatever it's called).
> >>>
> >>> FYI
> >>>
> >>>
> >>> This is where I inserted my code:
> >>>
> >>> /*
> ===========================================================================
> >>>  * Generate the codes for a given tree and bit counts (which need not
> be
> >>>  * optimal).
> >>>  * IN assertion: the array bl_count contains the bit length statistics
> for
> >>>  * the given tree and the field len is set for all tree elements.
> >>>  * OUT assertion: the field code is set for all tree elements of non
> >>>  *     zero code length.
> >>>  */
> >>> function gen_codes(tree, max_code, bl_count)
> >>> //    ct_data *tree;             /* the tree to decorate */
> >>> //    int max_code;              /* largest code with non zero
> frequency */
> >>> //    ushf *bl_count;            /* number of codes at each bit length
> */
> >>> {
> >>>   var next_code = new Array(MAX_BITS+1); /* next code value for each
> >>> bit length */
> >>>   var code = 0;              /* running code value */
> >>>   var bits;                  /* bit index */
> >>>   var n;                     /* code index */
> >>>
> >>>   /* The distribution counts are first used to generate the code values
> >>>    * without bit reversal.
> >>>    */
> >>>   for (bits = 1; bits <= MAX_BITS; bits++) {
> >>>     next_code[bits] = code = (code + bl_count[bits-1]) << 1;
> >>>   }
> >>>   /* Check that the bit counts in bl_count are consistent. The last
> code
> >>>    * must be all ones.
> >>>    */
> >>>   //Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
> >>>   //        "inconsistent bit counts");
> >>>   //Tracev((stderr,"\ngen_codes: max_code %d ", max_code));
> >>>
> >>>   for (n = 0;  n <= max_code; n++) {
> >>>     var len = tree[n*2 + 1]/*.Len*/;
> >>>     if (len === 0) { continue; }
> >>>     /* Now reverse the bits */
> >>>     tree[n*2]/*.Code*/ = bi_reverse(next_code[len]++, len);
> >>>
> >>>       if (tree!=static_ltree) {
> >>>           var v = tree[n*2];
> >>>           console.log('[' + n + ",'" + v.toString(2) + "'],");
> >>>       }
> >>>     //Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x
> (%x) ",
> >>>     //     n, (isgraph(n) ? n : ' '), len, tree[n].Code,
> next_code[len]-1));
> >>>   }
> >>>
> >>> }
> >>>
> >>> On Thu, Sep 11, 2014 at 11:55 AM, Joe Bogner <[email protected]>
> wrote:
> >>> > I think the prefix coding looks OK, but the 2 rules does not:
> >>> >
> >>> > I modified the code[1] to allow passing in a string and outputting
> the codes
> >>> >
> >>> > C:\temp>deflate ABCDEFGHIJKLMONPQRSTUVWXYZ
> >>> > code 65 : 0 00000000000000000000000000000000
> >>> > code 66 : 6 00000000000000000000000000000110
> >>> > code 67 : 8 00000000000000000000000000001000
> >>> > code 68 : 4 00000000000000000000000000000100
> >>> > code 69 : 22 00000000000000000000000000010110
> >>> > code 70 : 14 00000000000000000000000000001110
> >>> > code 71 : 30 00000000000000000000000000011110
> >>> > code 72 : 1 00000000000000000000000000000001
> >>> > code 73 : 17 00000000000000000000000000010001
> >>> > code 74 : 12 00000000000000000000000000001100
> >>> > code 75 : 9 00000000000000000000000000001001
> >>> > code 76 : 25 00000000000000000000000000011001
> >>> > code 77 : 5 00000000000000000000000000000101
> >>> > code 78 : 21 00000000000000000000000000010101
> >>> > code 79 : 13 00000000000000000000000000001101
> >>> > code 80 : 29 00000000000000000000000000011101
> >>> > code 81 : 3 00000000000000000000000000000011
> >>> > code 82 : 19 00000000000000000000000000010011
> >>> > code 83 : 11 00000000000000000000000000001011
> >>> > code 84 : 27 00000000000000000000000000011011
> >>> > code 85 : 7 00000000000000000000000000000111
> >>> > code 86 : 23 00000000000000000000000000010111
> >>> > code 87 : 15 00000000000000000000000000001111
> >>> > code 88 : 31 00000000000000000000000000011111
> >>> > code 89 : 2 00000000000000000000000000000010
> >>> > code 90 : 10 00000000000000000000000000001010
> >>> >
> >>> >
> >>> > I think it violates the consecutive rule... Each letter has the same
> >>> > frequency. ABCD have the same bit length. The order is off:
> >>> >
> >>> > If I sort it lexographically using javascript:
> >>> >
> >>> > JSON.stringify([['a','00000000000000000000000000000000'],
> >>> > ['b','00000000000000000000000000000110'],
> >>> > ['c','00000000000000000000000000001000'],
> >>> > ['d','00000000000000000000000000000100']].sort(function(x,y) { return
> >>> > x[1] - y[1] }))
> >>> >
> >>> >
> "[["a","00000000000000000000000000000000"],["d","00000000000000000000000000000100"],["b","00000000000000000000000000000110"],["c","00000000000000000000000000001000"]]"
> >>> >
> >>> > As you can see, the order comes out a,d,b,c
> >>> >
> >>> > I played around with a javascript implementation, pako[2]. It seems
> to
> >>> > work correctly:
> >>> >
> >>> > As you can see, it sorts lexographically
> >>> >
> >>> > JSON.stringify([[65,'1000001'],
> >>> > [66,'1000010'],
> >>> > [67,'1000011'],
> >>> > [68,'1000100'],
> >>> > [69,'1000101'],
> >>> > [70,'1000110'],
> >>> > [71,'1000111'],
> >>> > [72,'1001000'],
> >>> > [73,'1001001'],
> >>> > [74,'1001010'],
> >>> > [75,'1001011'],
> >>> > [76,'1001100'],
> >>> > [77,'1001101'],
> >>> > [78,'1001110'],
> >>> > [79,'1001111'],
> >>> > [80,'1010000'],
> >>> > [81,'1010001'],
> >>> > [82,'1010010'],
> >>> > [83,'1010011'],
> >>> > [84,'1010100'],
> >>> > [85,'1010101'],
> >>> > [86,'1010110'],
> >>> > [87,'1010111'],
> >>> > [88,'1011000'],
> >>> > [89,'1011001'],
> >>> > [90,'1011010']].sort(function(x,y) { return x[1] - y[1] }))
> >>> >
> >>> >
> "[[65,"1000001"],[66,"1000010"],[67,"1000011"],[68,"1000100"],[69,"1000101"],[70,"1000110"],[71,"1000111"],[72,"1001000"],[73,"1001001"],[74,"1001010"],[75,"1001011"],[76,"1001100"],[77,"1001101"],[78,"1001110"],[79,"1001111"],[80,"1010000"],[81,"1010001"],[82,"1010010"],[83,"1010011"],[84,"1010100"],[85,"1010101"],[86,"1010110"],[87,"1010111"],[88,"1011000"],[89,"1011001"],[90,"1011010"]]"
> >>> >
> >>> > All the values are sorted correctly.
> >>> >
> >>> > Here it is with the same ABCD example:
> >>> >
> >>> > var pako = require('pako');
> >>> > var binaryString = pako.deflate('ABCD', { to: 'string' });
> >>> > console.log(binaryString);
> >>> > var restored = pako.inflate(binaryString, { to: 'string' });
> >>> > console.log(restored);
> >>> >
> >>> > It successfully deflates and inflates itself
> >>> >
> >>> > x?♣A☺☺   ? mcÿ7♣A♫☻?☺♂
> >>> > ABCD
> >>> >
> >>> >
> >>> > Hope this helps...
> >>> >
> >>> > [1] -
> https://gist.github.com/joebo/a3c2932f0e5a7a0c3f07#file-deflate-c-L2613
> >>> > [2] - https://rawgit.com/nodeca/pako/master/dist/pako.js
> >>> >
> >>> > On Thu, Sep 11, 2014 at 11:33 AM, bill lam <[email protected]>
> wrote:
> >>> >> This is strange since every author must had decode its own encoded
> >>> >> data as a smoke test.
> >>> >>
> >>> >> Did you test if huffman code or bit lengths it produced was
> >>> >> correct or not, ie it is a prefix coding and it satisfy the 2
> >>> >> rules in rfc.
> >>> >>
> >>> >> Чт, 11 сен 2014, Joe Bogner написал(а):
> >>> >>> unfortunately the dynamic coding in the putty fork doesn't seem to
> work:
> >>> >>>
> >>> >>> deflate -c deflate.c > out
> >>> >>> deflate -d out
> >>> >>>
> >>> >>> decoding error: incorrect data checksum
> >>> >>>
> >>> >>>
> >>> >>> it works fine with static tables
> >>> >>>
> >>> >>> C:\temp>echo ABCD > ABCD
> >>> >>>
> >>> >>> C:\temp>deflate -c ABCD > out
> >>> >>>
> >>> >>> C:\temp>deflate -d out
> >>> >>> ABCD
> >>> >>>
> >>> >>> I added some debugging code to determine that deflating deflate.c
> >>> >>> would be a dynamic table...  Assuming it's broke, I probably
> wouldn't
> >>> >>> use it as a reference implementation after all
> >>> >>>
> >>> >>> On Thu, Sep 11, 2014 at 3:45 AM, bill lam <[email protected]>
> wrote:
> >>> >>> > the frequencies (guessing from bit lengths) should be something
> like 2 3 1 1
> >>> >>> >   (2 3 1 1) hcodes 'ABCD'
> >>> >>> >
> >>> >>> > the hard part is the inverse problem: how to get the huffman
> code with
> >>> >>> > prior knowing the bits for each symbol.  Your pointer to the
> putty
> >>> >>> > fork looks like helpful.  The comment is in lines 861 to 914,
> the code
> >>> >>> > itself in line 915 to 964. Do you know how to express it in J?
> >>> >>> > Thanks.
> >>> >>> >
> >>> >>> > On Thu, Sep 11, 2014 at 2:57 PM, Joe Bogner <[email protected]>
> wrote:
> >>> >>> >> Here a few other links ... after reading through the RFC. Not
> sure if
> >>> >>> >> they help, but just sharing from my own research into assisting
> on
> >>> >>> >> this topic
> >>> >>> >>
> >>> >>> >> https://github.com/evegard/pngview/blob/master/huffman.c#L54
> >>> >>> >>
> >>> >>> >> And a fork of the putty version with dynamic huffman coding:
> >>> >>> >>
> http://rc.quest.com/viewvc/putty/trunk/halibut/deflate.c?diff_format=s&revision=2&view=markup
> >>> >>> >>
> >>> >>> >> Or just generally googling some of the code from the RFC:
> >>> >>> >>
> https://www.google.com/search?q=next_code%5Blen%5D%2B%2B%3B&oq=next_code%5Blen%5D%2B%2B%3B&aqs=chrome..69i57.387j0j7&sourceid=chrome&es_sm=93&ie=UTF-8#q=next_code%5Blen%5D%2B%2B%3B&start=20
> >>> >>> >>
> >>> >>> >>
> >>> >>> >> Using the code from
> >>> >>> >> http://www.jsoftware.com/jwiki/Essays/Huffman%20Coding, I got
> stuck
> >>> >>> >> trying to match a simple example to the binary tree in the RFC:
> >>> >>> >>
> >>> >>> >> From the RFC:
> >>> >>> >>
> >>> >>> >>                   /\              Symbol    Code
> >>> >>> >>                          0  1             ------    ----
> >>> >>> >>                         /    \                A      00
> >>> >>> >>                        /\     B               B       1
> >>> >>> >>                       0  1                    C     011
> >>> >>> >>                      /    \                   D     010
> >>> >>> >>                     A     /\
> >>> >>> >>                          0  1
> >>> >>> >>                         /    \
> >>> >>> >>                        D      C
> >>> >>> >>
> >>> >>> >>
> >>> >>> >>
> >>> >>> >>    (4#1) hcodes 'ABCD'
> >>> >>> >> ┌───┬───┬───┬───┐
> >>> >>> >> │0 0│0 1│1 0│1 1│
> >>> >>> >> └───┴───┴───┴───┘
> >>> >>> >>
> >>> >>> >> Per the RFC, ideally that should match this?
> '00';'1';'011';'010'
> >>> >>> >>
> >>> >>> >>
> >>> >>> >> From there, it seems like a pretty straightforward exercise to
> >>> >>> >> transliterate the C code from the RFC into J code to recode the
> >>> >>> >> example to:
> >>> >>> >>
> >>> >>> >>
> >>> >>> >>             Symbol  Code
> >>> >>> >>             ------  ----
> >>> >>> >>             A       10
> >>> >>> >>             B       0
> >>> >>> >>             C       110
> >>> >>> >>             D       111
> >>> >>> >>
> >>> >>> >>
> >>> >>> >> I would probably start with a looping construct like what's in
> the RFC
> >>> >>> >> and then figure out a more J way to do it, but first I would
> need to
> >>> >>> >> figure out how to create the binary tree in that initial format.
> >>> >>> >>
> >>> >>> >> On Wed, Sep 10, 2014 at 7:41 PM, bill lam <[email protected]>
> wrote:
> >>> >>> >>> Thanks Joe,
> >>> >>> >>> putty only use zlib static huffman for encoding so that it
> does not build
> >>> >>> >>> any huffman dictionary table.
> >>> >>> >>>
> >>> >>> >>> The zlib static huffman code does not care about individual
> symbol's
> >>> >>> >>> frequency, it just encode 0 to 286 into bits, see section
> 3.2.6.
> >>> >>> >>>  On Sep 11, 2014 1:26 AM, "Joe Bogner" <[email protected]>
> wrote:
> >>> >>> >>>
> >>> >>> >>>> You've already likely considered this, but if it were me I
> would compare
> >>> >>> >>>> results to a working implementation. The one from putty seems
> pretty clean
> >>> >>> >>>> and standalone:
> >>> >>> >>>>
> https://raw.githubusercontent.com/grumpydev/PortablePuTTY/master/SSHZLIB.C
> >>> >>> >>>> . I was able to compile it on windows no problem and I assume
> it'd be fine
> >>> >>> >>>> on linux as well.
> >>> >>> >>>>
> >>> >>> >>>> On Wed, Sep 10, 2014 at 1:00 PM, Raul Miller <
> [email protected]>
> >>> >>> >>>> wrote:
> >>> >>> >>>>
> >>> >>> >>>> > I think the use of the term "consecutive" rather than
> "sequential" is
> >>> >>> >>>> > telling.
> >>> >>> >>>> >
> >>> >>> >>>> > The described algorithm is: compute the huffman code
> lengths:
> >>> >>> >>>> >    #@>F1 hcodes A1
> >>> >>> >>>> > 1 3 7 7 6 6 6 6 6 6 6 2
> >>> >>> >>>> >
> >>> >>> >>>> > Then assign ascending huffman codes first in length order
> and then
> >>> >>> >>>> > within codes of the same length.
> >>> >>> >>>> >
> >>> >>> >>>> > Taken literally, that might be something like this:
> >>> >>> >>>> >
> >>> >>> >>>> > H=: 4 :0
> >>> >>> >>>> >   L=.#@> x hcodes y
> >>> >>> >>>> >   U=.~.L
> >>> >>> >>>> >   ;<@(({.{.U e.~i.&.<:@{.)<@:+"1-@{.{."1 #:@i.@#)/.~L
> >>> >>> >>>> > )
> >>> >>> >>>> >
> >>> >>> >>>> >    ":@>F1 H A1
> >>> >>> >>>> > 0
> >>> >>> >>>> > 1 1 0
> >>> >>> >>>> > 1 1 1 0 0 1 0
> >>> >>> >>>> > 1 1 1 0 0 1 1
> >>> >>> >>>> > 1 1 1 0 0 0
> >>> >>> >>>> > 1 1 1 0 0 1
> >>> >>> >>>> > 1 1 1 0 1 0
> >>> >>> >>>> > 1 1 1 0 1 1
> >>> >>> >>>> > 1 1 1 1 0 0
> >>> >>> >>>> > 1 1 1 1 0 1
> >>> >>> >>>> > 1 1 1 1 1 0
> >>> >>> >>>> > 1 0
> >>> >>> >>>> >
> >>> >>> >>>> > But is this correct? Is it actually safe to leave the
> results like
> >>> >>> >>>> > this - with all codes of the same length being consecutive
> to each
> >>> >>> >>>> > other?
> >>> >>> >>>> >
> >>> >>> >>>> >    F (hcodes -:&:(#@>) H) A
> >>> >>> >>>> > 0
> >>> >>> >>>> >
> >>> >>> >>>> > No.
> >>> >>> >>>> >
> >>> >>> >>>> > So... "consecutive" must refer only to the values used and
> not their
> >>> >>> >>>> > order within the result.
> >>> >>> >>>> >
> >>> >>> >>>> > Perhaps something like this:
> >>> >>> >>>> >
> >>> >>> >>>> > deflatecodes=:4 :0
> >>> >>> >>>> >   L=.#@> x hcodes y
> >>> >>> >>>> >   U=.~.L
> >>> >>> >>>> >   R=. ;<@(({.{.U e.~i.&.<:@{.)<@:+"1-@{.{."1 #:@i.@#)/.~L
> >>> >>> >>>> >   R/:;(</. i.@#)L
> >>> >>> >>>> > )
> >>> >>> >>>> >
> >>> >>> >>>> >    F (hcodes -:&:(#@>) deflatecodes)  A
> >>> >>> >>>> > 1
> >>> >>> >>>> >
> >>> >>> >>>> > There should be a better way of doing this, but this should
> at least
> >>> >>> >>>> > get you started.
> >>> >>> >>>> >
> >>> >>> >>>> > Thanks,
> >>> >>> >>>> >
> >>> >>> >>>> > --
> >>> >>> >>>> > Raul
> >>> >>> >>>> >
> >>> >>> >>>> >
> >>> >>> >>>> > On Wed, Sep 10, 2014 at 10:45 AM, bill lam <
> [email protected]> wrote:
> >>> >>> >>>> > > For huffman coding used in zlib:
> >>> >>> >>>> > > https://www.ietf.org/rfc/rfc1951.txt section 3.2.2.
> >>> >>> >>>> > >
> >>> >>> >>>> > >  The Huffman codes used for each alphabet in the "deflate"
> >>> >>> >>>> > >  format have two additional rules:
> >>> >>> >>>> > >
> >>> >>> >>>> > >   * All codes of a given bit length have lexicographically
> >>> >>> >>>> > >   consecutive values, in the same order as the symbols
> >>> >>> >>>> > >   they represent;
> >>> >>> >>>> > >
> >>> >>> >>>> > >   * Shorter codes lexicographically precede longer codes.
> >>> >>> >>>> > > I tried jwiki hcodes in
> >>> >>> >>>> > > I try Roger's essay
> >>> >>> >>>> > > http://www.jsoftware.com/jwiki/Essays/Huffman%20Coding
> >>> >>> >>>> > >
> >>> >>> >>>> > > hc=: 4 : 0
> >>> >>> >>>> > > if. 1=#x do. y
> >>> >>> >>>> > > else. ((i{x),+/j{x) hc (i{y),<j{y [ i=. (i.#x) -. j=.
> 2{./:x end.
> >>> >>> >>>> > > )
> >>> >>> >>>> > >
> >>> >>> >>>> > > hcodes=: 4 : 0
> >>> >>> >>>> > > assert. x -:&$ y           NB. weights and words have
> same shape
> >>> >>> >>>> > > assert. (0<:x) *. 1=#$x    NB. weights are non-negative
> >>> >>> >>>> > > assert. 1 >: L.y           NB. words are boxed not more
> than once
> >>> >>> >>>> > > w=. ,&.> y                 NB. standardized words
> >>> >>> >>>> > > assert. w -: ~.w           NB. words are unique
> >>> >>> >>>> > > t=. 0 {:: x hc w           NB. minimal weight binary tree
> >>> >>> >>>> > > ((< S: 0 t) i. w) { <@(1&=)@; S: 1 {:: t
> >>> >>> >>>> > > )
> >>> >>> >>>> > >
> >>> >>> >>>> > > but the coding produced is malformed for zlib. eg,
> >>> >>> >>>> > > this is what I ran into trouble
> >>> >>> >>>> > >
> >>> >>> >>>> > > f1=: 1 256 17 1 1 9 1
> >>> >>> >>>> > > f2=: 2 1 0 1 255 0 1536
> >>> >>> >>>> > > F=: ,/(f1#f2)
> >>> >>> >>>> > > A=: i.286
> >>> >>> >>>> > >
> >>> >>> >>>> > > F hcodes A
> >>> >>> >>>> > >
> >>> >>> >>>> > > Or a shorter example
> >>> >>> >>>> > >
> >>> >>> >>>> > > A1=: i.12
> >>> >>> >>>> > > F1=: 2 1 0 0 0 0 0 0 0 0 0 1
> >>> >>> >>>> > >
> >>> >>> >>>> > > F1 hcodes A1
> >>> >>> >>>> > >
> >>> >>> >>>> > > Any idea?
> >>> >>> >>>> > >
> >>> >>> >>>> > > --
> >>> >>> >>>> > > regards,
> >>> >>> >>>> > > ====================================================
> >>> >>> >>>> > > GPG key 1024D/4434BAB3 2008-08-24
> >>> >>> >>>> > > gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3
> >>> >>> >>>> > > gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3
> >>> >>> >>>> > >
> ----------------------------------------------------------------------
> >>> >>> >>>> > > For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>> >>>> >
> ----------------------------------------------------------------------
> >>> >>> >>>> > For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>> >>>> >
> >>> >>> >>>>
> ----------------------------------------------------------------------
> >>> >>> >>>> For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>> >>>>
> >>> >>> >>>
> ----------------------------------------------------------------------
> >>> >>> >>> For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>> >>
> ----------------------------------------------------------------------
> >>> >>> >> For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>> >
> ----------------------------------------------------------------------
> >>> >>> > For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>>
> ----------------------------------------------------------------------
> >>> >>> For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> >>
> >>> >> --
> >>> >> regards,
> >>> >> ====================================================
> >>> >> GPG key 1024D/4434BAB3 2008-08-24
> >>> >> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3
> >>> >> gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3
> >>> >>
> ----------------------------------------------------------------------
> >>> >> For information about J forums see
> http://www.jsoftware.com/forums.htm
> >>> ----------------------------------------------------------------------
> >>> For information about J forums see http://www.jsoftware.com/forums.htm
> >>
> >> --
> >> regards,
> >> ====================================================
> >> GPG key 1024D/4434BAB3 2008-08-24
> >> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3
> >> gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3
> >> ----------------------------------------------------------------------
> >> For information about J forums see http://www.jsoftware.com/forums.htm
> > ----------------------------------------------------------------------
> > For information about J forums see http://www.jsoftware.com/forums.htm
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm

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