Buying Replica Watches Lesson 3
Rolex Oyster Perpetual has the function of perpetual calendar. Perpetual calendar basically means that it is able to tell that date without going wrong. The normal 3 o'clock date on your watch are dummy calendars meaning every month will have 31 days. Let's say we're in April and April only have 30 days you will have to adjust the date so that it doesn't strike 31.
Basically, the perpetual calendar works with a formula:
Calculating the day of the week given the date.
The formula uses the fact that each year begins one day later than the previous except for leap years. The days in a leap year are 2 days later except for January and February where it is one day later. Since the year values increase by one we can create a sequence by adding the year to the year divided by 4 dropping the fraction. This sequence increases by 1 every year except every 4 years where it increases by 2. This sequence will work for the years 1901 through 2099 only since 1900 and 2100 are not leap years.
A table is needed to get the relative day of week of the first of each month relative to the first day of a year.
Month 1 2 3 4 5 6 7 8 9 10 11 12
Rel day 0 3 3 6 1 4 6 2 5 0 3 5
Now for the formula (example for 2006/3/15 ).
Add the following: The 4 digit year (2006). The integer portion of the year divided by 4 (501). The relative month code (3). The day of the month (15). If it is a leap year and January or February then subtract 1 (0). Adjust the relative week day by subtracting 2 (2525-2). Divide by 7 keeping the remainder (3).
Use this number to find the day as follows:
0-Sunday 1-Monday 2-Tuesday 3-Wednesday 4-Thursday 5-Friday 6-Saturday
Corresponding months "Corresponding months" are those months within the calendar year that start on the same day. For example, September and December correspond, because September 1 falls on the same day as December 1. Months can only correspond if the number of days between their first days is divisible by 7, or in other words, if their first days are a whole number of weeks apart. For example, February corresponds to March because February has 28 days, a number divisible by 7, 28 days being exactly four weeks. In a leap year, January and February correspond to different months than in a common year since February 29 means each subsequent month starts a day later.
Here's how the months correspond:
- Common year
- January and October.
- February, March and November.
- April and July.
- No month corresponds to August.
- Leap year
- January, April and July.
- February and August.
- March and November.
- No month corresponds to October.
- All years
- September and December.
- No month corresponds to May or June.
Note that in the months table below, corresponding months have the same number, a fact which follows directly from the definition.
Corresponding years
There are 7 possible days that a year can start on, and leap years will alter the day of the week after Feb 29. This means that there are 14 configurations that a year can have. For example, 2007 is a common year starting on monday, meaning that 2007 corresponds to the 2001 calendar year. 2008, on the other hand, will be a leap year starting on tuesday, meaning that the year starts off corresponding to 2002, but after February, corresponds to 2003.
Mental calculation An easy way to do the calculation in your head is to imagine the year starts on March 1 rather than Jan 1 (as it did in Roman times), so that the extra day in a leap year is the last day, rather than occurring in the middle of the year. This removes the need to do different calculations for a leap year. It leads to, "day 0" described above being the last day of February.
April 4, June 6, Aug 8, Oct 10 and Dec 12, all occur on the same day as day 0 (note that April is the 4th month, June the 6th, August the 8th, etc).
May 9 & Sep 5 are also the same day as day 0 (May is the 5th month and September the 9th — the 9th day of the 5th month and the 5th day of the 9th month).
July 11 and Nov 7 are the same day as day 0 (the 7th and 11th months, respectively -- think of the 7-11 shops).
However, if one regards the new year as beginning onMarch 1 one has a simpler situation for February and January. Day 0 occurs on Jan 16 and Feb 6, which are the same day of the week as the previous last day of February (i.e. last year's Doomsday) for every year.
Also within each year beginning March 1, five months is always exactly 153 days and hence one day short of a whole number of weeks. This gives rise to the following dates for day 0:
Month +5 months -5 months +10 Months April 4 September 5 February 6 June 6 November 7 August 8 January 9 March 7 October 10 May 9 December 12 July 11
So if you can figure out what day "day 0" is, you can quickly find a date in any month that falls on the same day, and you only have to add or subtract a few days to get to any other day in the month.
Finding day 0 for a given year
First memorise this: in 2000, day 0 was a Tuesday. Every century, day 0 changes according to the following pattern: Tuesday, Sunday, Friday, Wednesday every 400 years; i.e., in 2100 day 0 will be Sunday; in 1900 it was Wednesday.
Every common year, day 0 moves forward one day, and two days every leap year.
The following also apply within any century beginning with a year ending with 00:
- Every four years, day 0 moves two days earlier. Thus, February 29, 2004 is a Sunday; February 29, 2008 is a Friday; February 29, 2012 is a Wednesday, etc.
- Every twelve years, day 0 moves one day later. Thus February 29, 2012 is a Wednesday, February 29, 2024 is a Thursday etc.
- Every twenty-eight years the calendar returns to the same day Thus, February 29, 1972, 2000, 2028, 2056, 2084 are all Tuesdays.
Example
So let's say it is desired to know what day June 3 2017 will be. Day 0 for 2000 was a Tuesday, in 2012 it will be Wednesday, 2013 will be Thursday, 2014 Friday, 2015 Saturday, 2016 (a leap year) Monday, and 2017 Tuesday; June is the 6th month, so the 6 June is a Tuesday. Three days earlier is Saturday.
I hope this gives you a basic understanding of how the perpetual calendar works. Well obviously it would be a rather complicated issue when we're talking about the this complication as there will be a myriad of gears to enable this to work. Just to give you an idea :)
My point here is that rolex replica watches will never be able to imitate this complication.
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Thanks monkey for your company throughout the week :) Sunday was the best and thanks for washing the car and house together! It felt great doing little little things together, and not to mention bombing that uncle while we were jogging :)
By the way forbidden kingdom was great. Think Never Ending Story.
Bomb! Foam!