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From "Robert Hulbert"<bob951...@gmail.com>
Subject Re: Table Formula Manipulation and Matrix Function Implementation in HSSF/XSSF
Date Wed, 28 Jun 2017 22:35:40 GMT
Correction, I meant to say array formulas. For example, when I attempted testing component
binary operations (+,-,*,/) using array formulas (formula over an area w/ CTRL+SHIFT+ENTER),
it evaluated to [!VALUE] in the cell where the formula was and empty string in subsequent
cells.

On 2017-06-27 15:59 (-0700), Greg Woolsey <greg.woolsey@gmail.com> wrote: 
> I implemented the current table formula handling, based on a patch I found
> languishing in the bug database.  It's been a year or so, but here's what I
> remember:
> 
> Data Table syntax works in most cases, but there is definitely room for
> more test cases looking for bugs in less common scenarios - Unicode in
> table header names, characters requiring quoting, references to the current
> or external workbooks are some I can think of off the top.
> 
> There are exceptions and JavaDoc notes in many places stating array
> formulas are not supported, and some open bugs about functions that work
> only partially or incorrectly because of incomplete array formula support.
> For example you can set array formulas for a sheet, but POI doesn't
> evaluate them when calculating.
> 
> I don't think there is much support at all currently for anything matrix
> related.  Parsing array syntax will be a tricky challenge, but if done
> would likely allow a good portion of array/matrix function implementations
> without much further fuss.
> 
> Table formula syntax is not allowed by Excel in places like chart
> definitions.  If someone wanted to work on functionality similar to that in
> Excel that can attempt to infer table/chart relationships, and thus offer
> some support for automatically adjusting chart definitions based on table
> additions/deletions, that would be an amazingly helpful feature to many
> users, I suspect (and myself for sure! :)  )
> 
> Somewhere on one of the mailing lists was a good collection of links to
> pages and videos related to implementing functions in POI, but I'm failing
> to find them right now.
> 
> On Tue, Jun 27, 2017 at 1:01 PM Hulbert, Robert Douglas <hulbert2@llnl.gov>
> wrote:
> 
> > Hi,
> >
> > I'm a summer student at Lawrence Livermore National Laboratory and was
> > hired to find or implement POI's table formulas and matrix functions.
> >
> > Over the last week or so, I have checked the POI page/Contributor
> > guidelines and have looked through the source code for handling this
> > functionality.
> >
> > Is anyone still interested in this functionality? If not, is there any
> > documentation on where this aspect left off?
> >
> > Thank you so much for any help you can give!
> >
> > Best Regards,
> > Robert Hulbert
> >
> 

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