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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Passing values from structure arrays to a generic geometrical mean function
Date: Mon, 30 Jan 2017 12:19:29 -0800
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Alla _ <modelling.data@gmail.com> writes:
[...]
> And, to Keith, I am a girl :)

I'm aware.  If I've used an incorrect pronoun, I apologize, but I'm not
aware that I have, nor do I see anything from me in this post or the few
of its direct ancestors I bothered to check.

[...]

> double mean_twonums(double number1, double number2)
> {   
> // if both abs values of numbers are between 1 and 0  
> if(   (fabs(number1) < 1 && fabs(number1) > 0)
>      && (fabs(number2) < 1 && fabs(number2) > 0) )
>   {
>       number1 += 1.0;
>       number2 += 1.0;
>
>       return pow((number1*number2), 1.0/2) - 1;
>   }
>  // if any number is negative return simple arithm average
>   if(number1 < 0 || number2 < 0)
>       return (number1+number2)/2;
>  //compute geo mean for any other cases
>   return pow((number1*number2), 1.0/2);
> }

I can't comment on whether this function is meaningful in financial
terms, but I find the name "mean_twonums" misleading at best.
The name strongly implies that it computes the mean of two numbers,
which should be as simple as
    return (number1 + number2) / 2.0;
for an arithmetic mean, or
    return sqrt(number1 * number2);
for a geometric mean.  There are other kinds of means, such as the
harmonic mean, but the value computed by this function doesn't resemble
any of them.

What this function actually does strikes me as quite arbitrary,
but that's merely a statement about my misunderstanding.  If this
mathematical function is actually called a "mean" in the field of
finance, then I suppose my objection is with financial terminology.
If it's not called a "mean", then I would hope that there's some
coherent name for it.

I seem to recall you also had a function called something like
"geomean()" that computed something other than a geometic mean.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"