% change = ( (present - past) / past ) * 100
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. > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org" _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"