Re: [office-formula] AVEDEV

[Andreas J Guelzow <aguelzow@math.concordia.ab.ca>]

On Sat, 2009-12-26 at 16:20 -0500, Patrick Durusau wrote:
> Greetings!
> 
> Lest we get too focused on the financial functions, can anyone tell me 
> what is wrong with the following?
> 
> AVEDEV - Calculates the average of the absolute deviations of the values 
> in list.
> 
> Yes, it should read, "the values in *a* list." but that's just poor 
> writing and I can fix  that.
> 
> What else is problematic about this function and its definition in 
> OpenFormula?
> 

> 
> Excluding the math formula, our text in full reads:

To the math formula we obviously need to add what n, x_i and x^bar are.
BUt then the math formula will define this function. 

> 
> > *Summary:* Calculates the average of the absolute deviations of the 
> > values in list.
> >
> > *Syntax:* AVEDEV( { /NumberSequenceList/ N }^+ )
> >
> > *Returns:* Number
> >
> > *Constraints:* None.
> >
> 1) Average - not defined.

that's only in the non-normative summary. so there is no need to define
that. (The formula given should explain everything!)

> 
> 2) Absolute deviation - not defined

ditto

> 
> 3) Values - not defined (what is the standard deviation of string 
> values, one from the other?)

the argument is a NumberSequenceList, so there are only numbers.
(Conversion of strings in teh argument to a NumberSequenceList is
defined elsewhere.)

> 
> 4) Values or NumberSequenceList?

as for 1)

> 
> 5) Calculates - not defined

as for  1)

> 
> 6) Calculates as opposed to return, returns, compute, computes, finds?

should really be none of the above

> 
> 7) No constraints? Suspect that values being numbers (see #8 on present 
> lack of definition) is one but see #4.

NumberSequenceList

So there are no constraints! There is implicit conversion happening
which is defined elsewhere.

> 
> 8) Returns Number? (Recalling that number is "defined" as "A number is 
> simply a numeric value such as 0, -4.5, or $1000." That's an 
> illustration, not a definition.

You can't be serious. Do you really want to define inside OpenFormula
what a number is? Since part 1 uses the terms number and numbering a
large number of times, we could refer to its definition of "number" (of
course it doesn't define "number" either.

> So, when I apply AVEDEV to a list of 
> numbers, an application could return a monetary amount?

you are confusing formulas and formatting. ANd of course in lots of
spreadsheets the return value of AVEDEV is (formatted as) a menetary
amount.

> Granting that 
> might make sense if the input was a series of monetary amounts but I 
> don't see a limitation here that prevents a string of integers having an 
> AVEDEV result of $42.

so what's the problem with that?
> 
> Not to exclude the math formula even though I am not including it in 
> this email:
> 
> Math Formula
> 
> 9) In order for this to be useful, simply reproducing it is 
> insufficient. Formulas are defined to be useful assuming particular 
> inputs and ranges on those inputs. As well as outputs. We don't have to 
> keep repeating them but we do need to define those inputs, limits and 
> outputs.
> 
> 10) What precision required is not specified (not really the fault of 
> the equation but seemed appropriate to mention here).

We address precision elsewhere (2.6). Among some things is that the
table:precision-as-shown setting affects this.

> 
> Note that fixing many of these issues for AVEDEV fixes the same issue 
> for other functions.
> 
> This should not be seen as being discouraging. The hard part, deciding 
> what needs to be defined and gathering up an enormous amount of 
> information on each part has already been done. Plus we are close enough 
> to say what remains to be defined to fully specify the functions in 
> OpenFormula.
> 

Andreas
-- 
Andreas J. Guelzow
Concordia University College of Alberta