I have been running into problems with sparse arrays. Since I cannot
reproduce them except in a large example, I am looking for the wisdom of
the community on a couple of issues.
1. Boolean matrix multiplication (+./ .*.). This seems to work some but
not all of the time, and then I get a nonce error. I have been using
*@:(+/ .*) as a substitute.
2. Non-unique sparse elements. I get this error from time to time when I
think I have been doing legitimate sparse array operations. I would have
more of a clue if I knew what it meant. The example in the list of error
messages is
($.i.4){i.4 2
with explanation "the sparse element of a sparse array must be an atom".
Can anyone relate this to the example? The simplest one of this type that
produces the error is ($.i.2){i.2 2 .
Best wishes,
John
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