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Subject: Re: [office-formula] AVEDEV
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
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