RE: [office-formula] Non-Scalar Evaluation and References

[Eric Patterson <ericpa@exchange.microsoft.com>]

I think an example may be useful for discussion purposes (not for inclusion in the spec).

If you put the values 1, 2, 3 in Cells A1:A3 respectively and 4,5,6 in B1:B3:

        A       B
1       1       4
2       2       5
3       3       6


Then put the formula =A1:A3+B1:B3 in different cells, you will see different results:

In F1, Result 5
In F2, Result 7
In B6, Result Error
In D7, Result Error

Note: Named expressions can also use implicit intersection when defined using relative references.

-Eric


-----Original Message-----
From: Patrick Durusau [mailto:patrick@durusau.net]
Sent: Tuesday, February 09, 2010 7:05 AM
To: office-formula@lists.oasis-open.org
Subject: [office-formula] Non-Scalar Evaluation and References

Greetings!

OK, to continue with non-scalar evaluations and references.

A reminder, we start off with:

>   1.
>
>       Evaluation as an implicit intersection of the argument with the
>       expression's evaluation position.
>
Actually that's a lie, we start with:

> Non-scalar values passed as arguments to functions are evaluated by
> intersection or iteration.
>
Which isn't true either. Non-scalar values are either evaluated as matrices or not. No reason to invent terms.

Anyway, back to non-scalar evaluation and references.

Let me say the principle and see if I get that right:

An expression occurs in some particular cell and that expression is a function that has a reference as its input. (OK so far?)

The value returned to the function is the "intersection" of the reference with the cell where the reference occurs.

If the cells specified by the reference don't intersect with the cell where the reference occurs, the value #VALUE is returned.

Yes?

The nature of the reference, whether row-vector or column-vector, isn't relevant.

Unless the intent was to limit those references to column and row vectors but then we would have to say that wouldn't we?

So I would restate References to read:

***
If a reference is passed to a function and not evaluated as a matrix, the value at the intersection of the cell where the reference occurs with a cell in the reference, if any, is returned to the function.

If there is no intersection between the cell where the reference occurs with a cell in the reference, the value #VALUE is returned. (full stop)
***

Shorter and to my way of thinking much clearer than what we have now.
For one thing it doesn't have all the undefined references ("evaluation position's row" for example).

BTW, looking ahead, we can drop the reference to ODF 8.13 table:number-matrix-column-spanned for the more general:

2) Matrix evaluation

Which makes it more general to all OpenFormula evaluators.

I have to re-write the next section to not use display as the basis for the operations but that comes next.

Hope everyone is having a great day!

Patrick

--
Patrick Durusau
patrick@durusau.net
Chair, V1 - US TAG to JTC 1/SC 34
Convener, JTC 1/SC 34/WG 3 (Topic Maps)
Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300 Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps)


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