On Monday, 29 July 2013 at 10:15:31 UTC, JS wrote:

On Thursday, 25 July 2013 at 21:27:47 UTC, Walter Bright wrote:On 7/25/2013 11:49 AM, Dmitry S wrote:I am also confused by the numbers. What I see at the end ofthe article is"21.56 seconds, and the latest development version does it in12.19", which isreally a 43% improvement. (Which is really great too.)## Advertising

21.56/12.19 is 1.77, i.e. a >75% improvement in speed. A reduction in time would be the reciprocal of that.Actually, it is a 43% speed improvement. 0.43*21.56 = 9.27sSo if it is 43% faster, it means it's reduced the time by 9.27sor, 21.56 - 9.27 = 12.28 seconds total.Now, if we started at 12.28 seconds and it jumped to 21.56 thenit would be 21.56/12.19 = 1.77 ==> 77% longer.21.56/12.19 != 12.19/21.56. The order matters.To make it obvious. Suppose the running time is 20 seconds. Youoptimize it, it is 100% **faster**(= 1.0*20 = 20s seconds),then it takes 0 seconds(20 - 20).

That is how you fail a physics class. s = d/t => t = d/s 100% increase in s = 2*s let s_new = 2*s t_new = d / s_new let d = 1 program (s is measured in programs / unit time_ therefore: t_new = 1 / s_new = 1 / (2 * s) = 0.5 * 1/s = 0.5 * t

`Seriously... Walter wouldn't have got his mechanical engineering`

`degree if he didn't know how to calculate a speed properly.`