Re: [office] Formula: test cases

[Patrick Durusau <patrick@durusau.net>]

Rob,

robert_weir@us.ibm.com wrote:

>
> An interesting example of how others have approved this problem is the 
> functions in XPath 1.0.   Here's how James Clark describes the round() 
> function:
>
> "Function: number round(number)
>
> The round function returns the number that is closest to the argument 
> and that is an integer. If there are two such numbers, then the one 
> that is closest to positive infinity is returned. If the argument is 
> NaN, then NaN is returned. If the argument is positive infinity, then 
> positive infinity is returned. If the argument is negative infinity, 
> then negative infinity is returned. If the argument is positive zero, 
> then positive zero is returned. If the argument is negative zero, then 
> negative zero is returned. If the argument is less than zero, but 
> greater than or equal to -0.5, then negative zero is returned."
>
> I always liked that definition.  Very complete. It is just text, with 
> no test suite, but the text is mainly a verbose English enumeration of 
> text cases.  Why not rwrite it as:
>
>
> "The round function returns the number that is closest to the argument 
> and that is an integer. If there are two such numbers, then the one 
> that is closest to positive infinity is returned.
>
> Examples:
>
> round(NaN) = NaN
> round(Inf) = Inf
> round (-Inf) = -Inf
> round(0) = 0
> round (-0) 0
> round (0.25) = -0"
>
> Isn't this just a difference of notation and one that is much easier 
> to read?  Interestingly in other parts of XPath, explicit examples are 
> given, such as in the definition of substring().
>
>  If needed we could probably write a Python script that would take all 
> of the test cases and generate English sentences for each one.  But is 
> that an improvement?
>
Err, well, I am supposed to be reading the formula proposal carefully 
but I guess I can take a break to reply. ;-)

Sure, if you pick your examples carefully, then a "test case" can appear 
to be clearer than a normative expression in English.

But, note that your "test cases" enumerates the entire range of possible 
values.

 From the "test cases" that I have examined in the proposal, that is not 
the case. That is they enumerate some "test" values and specify a result.

That isn't the same thing as abstractly specifying the rule for an 
entire range of values.

I am not wedded to the notion of expressing all the rules in English. 
But then I have spent a lot of time with markup theory proposals and so 
prior experience may color my perception of what is clearly expressed. ;-)

Hope you are having a great day!

Patrick


> -Rob
>
>
> Patrick Durusau <patrick@durusau.net> wrote on 03/29/2007 12:48:50 PM:
>
> > Bruce,
> >
> > Bruce D'Arcus wrote:
> >
> > >
> > > On Mar 29, 2007, at 12:26 PM, Patrick Durusau wrote:
> > >
> > >>> This seems like a reasonable point, and the crux of the matter.
> > >>>
> > >> Well, a reasonable point but not really the crux of the matter.
> > >
> > >
> > > By this I mean the central question is whether formulas constitute a  
> > > special case of sorts that would justify the approach. That, it 
> seems  
> > > to me, *is* the crux of the matter. General rules only work for  
> > > general cases.
> > >
> > Oh, OK, I stand corrected. Sorry, did not understand that to be your 
> point.
> >
> > Hmmm, well I doubt this is the first time that formulas (or other math
> > functions) have been specified. I will check with the usual suspects
> > (standards bodies) and see what I can turn up. Most of that stuff tends
> > to be unavailable online but I will see what I can turn up.
> >
> > Hope you are having a great day!
> >
> > Patrick
> >
> > PS: Would standards by mathematical associations count? Not ISO but
> > certainly similar in character.
> >
> > --
> > Patrick Durusau
> > Patrick@Durusau.net
> > Chair, V1 - Text Processing: Office and Publishing Systems Interface
> > Co-Editor, ISO 13250, Topic Maps -- Reference Model
> > Member, Text Encoding Initiative Board of Directors, 2003-2005
> >
> > Topic Maps: Human, not artificial, intelligence at work!
> >
> >
>

-- 
Patrick Durusau
Patrick@Durusau.net
Chair, V1 - Text Processing: Office and Publishing Systems Interface
Co-Editor, ISO 13250, Topic Maps -- Reference Model
Member, Text Encoding Initiative Board of Directors, 2003-2005

Topic Maps: Human, not artificial, intelligence at work!