3 ms·

Months are pretty well and exhaustively defined. There are 13 of them. It's just that it's not enough to say that there is a 3-month interval. You need to speci

Months are pretty well and exhaustively defined. There are 13 of them. It's just that it's not enough to say that there is a 3-month interval. You need to specify either the dates or the months. To say months shouldn't be used is sort of like saying that complex numbers or vectors shouldn't be used. They are absolutely useful. We just deal with their component parts separately.

orting 7y ago
A month is not a well defined unit. There are four different month units: 28, 29, 30, 31 days. If you do calculations respecting this there will be no problem. Complex numbers and vectors are not a good analogy.
- xelxebar 7y ago
  I believe you fail to grok GP's point. The mapping from "month" units to "days" units is well-defined. It's just some function that happens to be non-constant over the month ordinal. Heck, if we start down the "precise time definition" rabbit hole, though, then neither does "day" have some philosophically unassailable notion, cf. leap seconds. Even the unit of "second" ends up pulling in a whole heck of a lot of physics machinery just to nail down some semblance of rigor. Anyway, despite being such an intuitively simple and practically functional concept, the notion of time amd time measurement turns out to be suprisingly subtle and to have a fascinating history. I highly recommend jumping down that rabbit hole. Hehe Anyway, I'm surprised calc.exe doesn't calculate with and store dates using some kind of epoch time.
Piskvorrr 7y ago
Uh...October, November, December and Undecimber? I don't see the last one very often. (In other words, once you start delving into it, turns out it's neither simple nor unambiguous - which calendar? If Gregorian, when did the switch from Julian happen? Etc etc.)
- lagadu 7y ago
  I'm guessing he means that there's two distinct Februaries, in the gregorian calendar.
  - Piskvorrr 7y ago
    Yeah, that's also a possibility.
VMG 7y ago
Months should not be used to describe durations. The length of one month is not clearly defined. Edit: except when giving an approximation, which the program doesn't
boomlinde 7y ago
I think that you are missing the point. GP means to say that "a month" is poorly defined as a unit of duration, specifically. Not even ISO 8601 specifies what exactly a month means in terms of duration, despite specifying a duration description format that includes months. In some cases you can take "a month from now" to mean the same calendar day of the next month. This leaves what a month from January 31 means ambiguous, and also dependent on when the duration starts. You can take an easier route and say that a month is 30 days. Still, the duration is ambiguous because it depends on when it takes place (i.e. an interval), because of summer/winter time adjustment. You can say that it's 720 hours, but that's still dependent on the start of the duration because of leap seconds. In the end, the only way to describe a duration unambiguously regardless of its start time is with seconds. There is no such thing as a well defined duration for any other unit of time.

orting 7y ago

A month is not a well defined unit. There are four different month units: 28, 29, 30, 31 days. If you do calculations respecting this there will be no problem. Complex numbers and vectors are not a good analogy.

xelxebar 7y ago
I believe you fail to grok GP's point. The mapping from "month" units to "days" units is well-defined. It's just some function that happens to be non-constant over the month ordinal. Heck, if we start down the "precise time definition" rabbit hole, though, then neither does "day" have some philosophically unassailable notion, cf. leap seconds. Even the unit of "second" ends up pulling in a whole heck of a lot of physics machinery just to nail down some semblance of rigor. Anyway, despite being such an intuitively simple and practically functional concept, the notion of time amd time measurement turns out to be suprisingly subtle and to have a fascinating history. I highly recommend jumping down that rabbit hole. Hehe Anyway, I'm surprised calc.exe doesn't calculate with and store dates using some kind of epoch time.

Piskvorrr 7y ago

Uh...October, November, December and Undecimber? I don't see the last one very often. (In other words, once you start delving into it, turns out it's neither simple nor unambiguous - which calendar? If Gregorian, when did the switch from Julian happen? Etc etc.)

lagadu 7y ago
I'm guessing he means that there's two distinct Februaries, in the gregorian calendar.
- Piskvorrr 7y ago
  Yeah, that's also a possibility.

VMG 7y ago

Months should not be used to describe durations. The length of one month is not clearly defined. Edit: except when giving an approximation, which the program doesn't

boomlinde 7y ago

I think that you are missing the point. GP means to say that "a month" is poorly defined as a unit of duration, specifically. Not even ISO 8601 specifies what exactly a month means in terms of duration, despite specifying a duration description format that includes months. In some cases you can take "a month from now" to mean the same calendar day of the next month. This leaves what a month from January 31 means ambiguous, and also dependent on when the duration starts. You can take an easier route and say that a month is 30 days. Still, the duration is ambiguous because it depends on when it takes place (i.e. an interval), because of summer/winter time adjustment. You can say that it's 720 hours, but that's still dependent on the start of the duration because of leap seconds. In the end, the only way to describe a duration unambiguously regardless of its start time is with seconds. There is no such thing as a well defined duration for any other unit of time.