# Re: way way off topic

On Tue, Oct 23, 2012 at 05:52:02PM -0700, Gezeala M. Bacuño II wrote:
> % change = ( (present - past) / past ) * 100
>

yeah, this is exactly it for my "how much more is 16 than 15"
problem. or the ages example.

It's 6.6[bar-over .6]%  this is probably close to or exactly
what was the core of my C [argc, *srgv[]] program.   my error was in
not understanding the logic that polttropon has given below.  if/when
I ever find that v short exercise, THIS time, il'l remember to
'splain stuff in

/*
*/

>
> On Tue, Oct 23, 2012 at 5:07 PM, Gary Kline <kl...@thought.org> wrote:
> > On Tue, Oct 23, 2012 at 08:52:49AM +0200, Polytropon wrote:
> >> On Tue, 23 Oct 2012 11:31:18 +0700, Olivier Nicole wrote:
> >> > Gary,
> >> >
> >> > On Tue, Oct 23, 2012 at 11:20 AM, Gary Kline <kl...@thought.org> wrote:
> >> > >
> >> > > apologies up front for this math type quandary. I had it in a std C
> >> > > program,
> >> > > but 3+ hours of grepping havent found it.  I would have bet my last
> >> > > cent that I
> >> > > had a summary Somewhere, but cant find that either.
> >> > >
> >> > > here is the problem as best I can remember it.
> >> > >
> >> > >
> >> > >         let's say that john is 8 and his older friend, jim, is 22.
> >> > >         how much older is exact percentage terms is jim?
> >> >
> >> > That should be 22/8=2.75
> >> > Jim is 275% older than John
> >>
> >> Jim is 175% _older_. Why? Because 100% older means 16 years,
> >> as 100% refers to 8 years (8+8=16, 200% older is 8+8+8=24).
> >> Percentage is always a reference to something else, in this
> >> question, Jim's age in relation to John's. The word "older"
> >> means "adding percentage", refering to the base value of 8,
> >> "divided in 100 parts" (floating point considerations aside),
> >> to finally reach the value 22.
> >>
> >> If the question would be different, say, "What's the percentage
> >> of John's age regarding Jim's age?" In that case, it would be
> >> 8/22=0.3636 being 36%. Obvious: John's age is approximately
> >> 1/3 of Jim's age.
> >>
> >> The easiest way for creating the proper calculation is to refer
> >> to the equation
> >>
> >>                          percentage * 100
> >>       percentage value = ----------------
> >>                            base value
> >>
> >> and resolve it to whatever is required.
> >>
> >> --
> >> Polytropon
> >> Magdeburg, Germany
> >> Happy FreeBSD user since 4.0
> >> Andra moi ennepe, Mousa, ...
> >
> >
> >         yo; I THInk this is it. around line 4542 in my ~/.HowTo file::
> >
> >
> >
> > %%% find percent inc/dec [increase/decrease] between two numbers.
> >
> > Always figure the percentage of change relative to the original value!
> > For instance: * Suppose a certain item used to sell for seventy-five
> > cents a pound, you see that it's been marked up to eighty-one cents a
> > pound. What is the percent increase?
> >
> > First, I have to find the absolute
> > increase:
> > Reserved 81 - 75 = 6
> >
> > The price has gone up six cents. Now I can find the
> > percentage increase over the original price.
> >
> > This percentage increase is the relative change: 6/75 = 0.08
> > ...or an 8% increase in price per pound.
> >
> >
> >
> >         So I was wrong about ages or speed; it's the % betwen two ints;
> >         here, the inc/dec [or change] between 75 cents as compared to
> >         an inflated increase of 81 cents.
> >
> >         1.  find abs increase:  81-75 = 6;
> >         2   find the % increase over the *original* value. 6.0/75.0
> >         3.  percent increase using doubles is 0.08;  so a markup of six
> >             cents is an 8% rate.
> >
> >
> >         so: going back to the ages example with john bein 8, jim, 22.
> >         22-8 is 14.
> >         14.0/8.0 = 1.750000
> >
> >         175%.  jim is 175% times older than john.  which is what you found,
> >         polyt.  {I'll have to re-read your logic now that im awake..}
> >
> >         Or, how much more, in % is 16t than 15, it is 1.0/15.0 which is 6%.
> >         etc,  etc.
> >
> >         Hm.  that's 0 for gary, 729 for polytrop!!
> >
> >         Ah, life:: accept no substitutes.
> >
> >
> >
> >
> > --
> >  Gary Kline  kl...@thought.org  http://www.thought.org  Public Service Unix
> >               Twenty-six years of service to the Unix community.
> >
> > _______________________________________________
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--
Gary Kline  kl...@thought.org  http://www.thought.org  Public Service Unix
Twenty-six years of service to the Unix community.

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