the quote from the GNU coreutils manpages on Date Input Formats: "Our units of temporal measurement, from seconds on up to months, are so complicated, asymmetrical and disjunctive so as to make coherent mental reckoning in time all but impossible. Indeed, had some tyrannical god contrived to enslave our minds to time, to make it all but impossible for us to escape subjection to sodden routines and unpleasant surprises, he could hardly have done better than handing down our present system. It is like a set of trapezoidal building blocks, with no vertical or horizontal surfaces, like a language in which the simplest thought demands ornate constructions, useless particles and lengthy circumlocutions. Unlike the more successful patterns of language and science, which enable us to face experience boldly or at least level-headedly, our system of temporal calculation silently and persistently encourages our terror of time. ... It is as though architects had to measure length in feet, width in meters and height in ells; as though basic instruction manuals demanded a knowledge of five different languages. It is no wonder then that we often look into our own immediate past or future, last Tuesday or a week from Sunday, with feelings of helpless confusion." -Robert Grudin, Time and the Art of Living. http://www.gnu.org/software/coreutils/manual/coreutils.html#Date-input-forma... /kc On Sun, Jan 25, 2015 at 01:15:27PM -0500, Valdis.Kletnieks@vt.edu said:
And of course doing interval math across several years where you cross multiple leap seconds is even more problematic - for some corner cases that have an endppoint nearmidnight, doing a naive "timestamp in seconds +/- 86400 * number of days" can land you on the wrong *day*, with possibly serious consequences...
/kc -- Ken Chase - math@sizone.org Toronto