# Is 70ms 14 or 12% faster than 80ms ?

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## Is 70ms 14 or 12% faster than 80ms ?

 Is 70ms 14 or 12% faster than 80ms ? Reading many stackoverflow response, I am still confused. Most answers claimed (1 - 70/80), or 12.5% faster If the math is right, it is impossible to be 100% faster. 10 times faster (1000%) is meaningless (time is negative) I normally avoid using "percentage faster", and prefer ratio: Speed at 80/70 = 1.14X -- https://stackoverflow.com/questions/31506554/is-70-ms-14-or-12-faster-than-80-ms?noredirect=1&lq=1https://stackoverflow.com/questions/8127862/how-do-you-calculate-how-much-faster-time-x-is-from-time-y-in-terms-ofhttps://math.stackexchange.com/questions/716767/how-to-calculate-the-percentage-of-increase-decrease-with-negative-numbers/716770#716770
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 Am 15.05.2018 um 13:19 schrieb Albert Chan: > Is 70ms 14 or 12% faster than 80ms ? > > Reading many stackoverflow response, I am still confused. > Most answers claimed (1 - 70/80), or 12.5% faster > > If the math is right, it is impossible to be 100% faster. > 10 times faster (1000%) is meaningless (time is negative) > > I normally avoid using "percentage faster", and prefer ratio: > Speed at 80/70 = 1.14X > > it takes 12.5% less time that makes it 14.28...% faster (1 / (1-0.125)) -- Oliver
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 In reply to this post by Albert Chan The term "fast" refers to "speed". To express speed, you need to specify amount and time.If a process takes 70ms to complete, then it's speed is 14,29 times per second (1 / 0,07)If a process takes 80ms to complete, then it's speed is 12,5 times per second.so, the speed of 70ms is (14,29/12,5) times faster than 80ms's speed = 14,289 % faster....On Tue, May 15, 2018 at 8:19 AM, Albert Chan wrote:Is 70ms 14 or 12% faster than 80ms ? Reading many stackoverflow response, I am still confused. Most answers claimed (1 - 70/80), or 12.5% faster If the math is right, it is impossible to be 100% faster. 10 times faster (1000%) is meaningless (time is negative) I normally avoid using "percentage faster", and prefer ratio: Speed at 80/70 = 1.14X -- https://stackoverflow.com/questions/31506554/is-70-ms-14-or-12-faster-than-80-ms?noredirect=1&lq=1 https://stackoverflow.com/questions/8127862/how-do-you-calculate-how-much-faster-time-x-is-from-time-y-in-terms-of https://math.stackexchange.com/questions/716767/how-to-calculate-the-percentage-of-increase-decrease-with-negative-numbers/716770#716770 -- Alysson Cunha / AlyssonRPGhttp://www.rrpg.com.br - Jogue o tradicional RPG de mesa onlinehttp://www.alyssoncunha.com.br - Me conheça melhor
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 In reply to this post by Albert Chan On Tue, May 15, 2018 at 1:19 PM, Albert Chan wrote:> Is 70ms 14 or 12% faster than 80ms ?Times: t vs T, t = (1 - s)T, meaning t is s x 100% shorter than T.Speeds: v = 1/t vs V = 1/T, v = (1/(1 - s)) V = (1 + f)V, meaning v is f x 100% faster than V.Obviously 1/(1 - s) = (1 + f), so f = s / (1 - s), and s = f / (1 + f).With t = 70 and T = 80, s = 0.125, f = 0.143.> If the math is right, it is impossible to be 100% faster.Given f = 1 and T = 80, s = 0.5, t = 40.Cheers,V.
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 In reply to this post by Oliver Kroth >> Is 70ms 14 or 12% faster than 80ms ? >> >> Reading many stackoverflow response, I am still confused. >> Most answers claimed (1 - 70/80), or 12.5% faster >> >> --Albert > > it takes 12.5% less time > that makes it 14.28...% faster (1 / (1-0.125)) > > -- > Oliver Thanks.  Stack-overflow is wrong ! -- %faster should be relative to speed speed = 1/70= (100% + %faster)(1/80) %faster = 80/70 - 100% = 14.3% -- %slower should also be relative to speed -- Example: 70ms job now take 80ms speed = 1/80 = (100% - %slower)(1/70) %slower = 100% - 70/80 = 12.5% --> %slower will NEVER reach 100%
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 > speed = 1/70= (100% + %faster)(1/80) > %faster = 80/70 - 100% = 14.3% Just want to add:   % faster should only be use for small percentage Bruce Dawson recommend around 20% https://randomascii.wordpress.com/2018/02/04/what-we-talk-about-when-we-talk-about-performance/We don't say 100% faster, we say twice as fast -- the number is bigger, good for marketing -- using speed ratio is unambiguous (faster if ratio > 1) -- work well even if code run slower, say 0.96X -- trivial to calculate speed vs oldest version = 1.143 * 0.96 = 1.097X
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 If what everyone here say is true, "Lua Programming Gems" is wrong (unless it is trying to *redefine* the meaning of % faster) Quote from chapter 2, Lua Performance tips : https://www.lua.org/gems/sample.pdfWhen I say that a program is "X% times faster" than another it means that it runs in % less time. (A program 100% faster would take no time to run).  When I say that a program is "X% times slower" than another I mean that the other is % faster.  (A program 50% slower means that it takes twice the time). -- I ALWAYS use speed ratio, say 1.143X, to avoid this ambiguity
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 2018-05-15 23:20 GMT+02:00 Albert Chan <[hidden email]>: > If what everyone here say is true, "Lua Programming Gems" is wrong > (unless it is trying to *redefine* the meaning of % faster) > > Quote from chapter 2, Lua Performance tips : > https://www.lua.org/gems/sample.pdf> > When I say that a program is "X% times faster" than another it means > that it runs in % less time. (A program 100% faster would take no time > to run).  When I say that a program is "X% times slower" than another > I mean that the other is % faster.  (A program 50% slower means that > it takes twice the time). That tells you precisely how the the terms "faster" and "slower" are used _in that article_, in order to avoid misunderstanding by readers whose usage may be different. It is exactly the same kind of remark as: > I ALWAYS use speed ratio, say 1.143X, to avoid this ambiguity except that it does not confidently claim "ALWAYS".
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 On May 15, 2018, at 11:12 PM, Dirk Laurie <[hidden email]> wrote:When I say that a program is "X% times faster" than another it meansthat it runs in % less time. (A program 100% faster would take no timeto run).  When I say that a program is "X% times slower" than anotherI mean that the other is % faster.  (A program 50% slower means thatit takes twice the time).That tells you precisely how the the terms "faster" and "slower" areused _in that article_, in order to avoid misunderstanding by readerswhose usage may be different.… except he *defines* the phrase “X% times faster” but then *uses* the phrase “100% faster” and not “100% times faster”.I’m not entirely sure “X% times faster” is a good choice. What is “10% times faster” supposed to mean? It certainly *doesnt* mean “10% faster”, nor does it mean “1/10th times faster”.—Tim
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 2018-05-16 9:34 GMT+02:00 Tim Hill <[hidden email]>: > > > On May 15, 2018, at 11:12 PM, Dirk Laurie <[hidden email]> wrote: > > When I say that a program is "X% times faster" than another it means > that it runs in % less time. (A program 100% faster would take no time > to run).  When I say that a program is "X% times slower" than another > I mean that the other is % faster.  (A program 50% slower means that > it takes twice the time). > > > That tells you precisely how the the terms "faster" and "slower" are > used _in that article_, in order to avoid misunderstanding by readers > whose usage may be different. > > > … except he *defines* the phrase “X% times faster” but then *uses* the > phrase “100% faster” and not “100% times faster”. > > I’m not entirely sure “X% times faster” is a good choice. What is “10% times > faster” supposed to mean? It certainly *doesnt* mean “10% faster”, nor does > it mean “1/10th times faster”. Aha. Humpty Dumpty (the famous quote on what words mean)  is not enough for this discussion. We need the White Knight too (the nice distinctions on what the song is, what it is called, what its title is, and what the title of the song is called). Moreover, didn't Lewis Carroll in his alter ego as C.L.Dodgson, that eristic algebraist and logician, say something about precisely the topic of "times faster" and "times as fast as"? I'll have to re-read Curiousa Mathematica :-)
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 In reply to this post by Dirk Laurie-2 On May 16, 2018, at 2:12 AM, Dirk Laurie <[hidden email]> wrote:2018-05-15 23:20 GMT+02:00 Albert Chan <[hidden email]>:If what everyone here say is true, "Lua Programming Gems" is wrong(unless it is trying to *redefine* the meaning of % faster)That tells you precisely how the the terms "faster" and "slower" areused _in that article_, in order to avoid misunderstanding by readerswhose usage may be different.The article remove %faster ambiguity, but still is misleading.Readers will not know it can only be used _in that article_.I thought it were just a *reminder* of terms, not a re-definition.A better reminder is to say X% faster meant X% faster in speed.Another case of "faster" re-definition:https://www.livescience.com/27920-quantum-action-faster-than-light.htmlSpooky! Quantum Action Is 10,000 Times Faster Than LightHow fast do quantum interactions happen? Faster than light, 10,000 times fasterIt is exactly the same kind of remark as:I ALWAYS use speed ratio, say 1.143X, to avoid this ambiguityexcept that it does not confidently claim "ALWAYS".But I DO !Speed ratio is much more precise than "% faster"(Besides, I were un-sure what "% faster" meant ...)
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## Re: Is 70ms 14 or 12% faster than 80ms ?

 In reply to this post by Tim Hill On May 15, 2018, at 11:12 PM, Dirk Laurie <[hidden email]> wrote:When I say that a program is "X% times faster" than another it meansthat it runs in % less time. (A program 100% faster would take no timeto run).  When I say that a program is "X% times slower" than anotherI mean that the other is % faster.  (A program 50% slower means thatit takes twice the time).That tells you precisely how the the terms "faster" and "slower" areused _in that article_, in order to avoid misunderstanding by readerswhose usage may be different.… except he *defines* the phrase “X% times faster” but then *uses* the phrase “100% faster” and not “100% times faster”.I’m not entirely sure “X% times faster” is a good choice. What is “10% times faster” supposed to mean? It certainly *doesnt* mean “10% faster”, nor does it mean “1/10th times faster”.—TimGood catch !