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*Subject*: **RE: [office-formula] Implementation-defined, Unspecified, and Undefinedbehaviors in OpenFormula**

*From*:**robert_weir@us.ibm.com***To*: <dennis.hamilton@acm.org>*Date*: Fri, 12 Jun 2009 08:26:07 -0400

The language on precision is: "This specification does not, by itself, specify a numerical implementation model, though it does imply some minimal levels of accuracy for most functions. For example, an application cannot say that it implements the infix operator ?/? as specified in this document if it implements integer-only arithmetic. In practice, applications tend to use at least one IEEE 754-1985 binary floating-point representation, using at least the 64-bit representation and possibly larger widths for intermediate results. When IEEE 754 representations are used, results such as Inf (infinity) and Nan (not a number) are considered an Error value. Applications may use IEEE 854-1987 (which covers decimal arithmetic). In general, applications are encouraged to use appropriate standards for their numerical models. This means that applications will often not produce ?exact? results, but only approximate results for a large number of places." I think I would call this "implementation-defined" and we probably want to say that explicitly in cases like this. We might also wanb to rephrase this from a statement about the specification, "the specification does not...", to a statement about the implementation, e..g, "The numerical implementation model used by a conforming OpenFormula expression evaluator is implementation-defined", or something similar. -Rob "Dennis E. Hamilton" <dennis.hamilton@acm.org> wrote on 06/12/2009 01:52:18 AM: > > Subject: > > RE: [office-formula] Implementation-defined, Unspecified, and > Undefined behaviors in OpenFormula > > I recall "discretionary" being used in cases such as arithmetic precision, > maximum dimensions on tables, and other cases where an implementation may > place a limitation (e.g., on the maximum length of the dc:creator string, in > presented characters, that will be put into some user-readable > presentation). > > Although some implementation-defined aspects may be of this nature, it might > be useful to single them out. I certainly agree that there should be a > specification of how each conforming implementation handles > implementation-defined features. > > - Dennis > > -----Original Message----- > From: robert_weir@us.ibm.com [mailto:robert_weir@us.ibm.com] > Sent: Thursday, June 11, 2009 21:19 > To: office-formula@lists.oasis-open.org > Subject: Re: [office-formula] Implementation-defined, Unspecified, and > Undefined behaviors in OpenFormula > > [ ... ] > > I'd like to see us come up with a good reason why it is a good thing to > have a feature be implementation-defined. Saying "mathematicians > disagree" or "different implementations do different things" doesn't sound > like a particularly good reason. I think it is expected that > implementations will need to change their code to implement OpenFormula. > I'd be astonished if the did not. > > That said, I'm sure we can come up with some good reasons. For example, > the exact numeric precision is not specified. This is not because having > consistent floating point behavior would not be a good thing. The issue > is that enforcing such uniformity, across machine architectures, would > essentially mean that we avoid on-chip floating point and do it via > emulation, which would perform poorly and be expensive to implement, with > little incremental user benefit. > > That's the analysis I'd like to see: What is the user benefit if we > eliminated these differences versus what would be the downside. > > [ ... ] >

**Follow-Ups**:**Re: [office-formula] Implementation-defined, Unspecified, and Undefinedbehaviors in OpenFormula***From:*"David A. Wheeler" <dwheeler@dwheeler.com>

**References**:**Implementation-defined, Unspecified, and Undefined behaviors in OpenFormula***From:*robert_weir@us.ibm.com

**Re: [office-formula] Implementation-defined, Unspecified, and Undefinedbehaviors in OpenFormula***From:*"David A. Wheeler" <dwheeler@dwheeler.com>

**Re: [office-formula] Implementation-defined, Unspecified, and Undefinedbehaviorsin OpenFormula***From:*robert_weir@us.ibm.com

**RE: [office-formula] Implementation-defined, Unspecified, and Undefined behaviors in OpenFormula***From:*"Dennis E. Hamilton" <dennis.hamilton@acm.org>

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