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this is a day of week calculate tool for the TI-84+ CE that works correctly, even with dates of before the change to the Gregorian calendar. So it works for both the Julian dates and the Gregorian dates

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PrivacyDragon/Day-of-Week-TI-84Plus-CE

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Day-of-Week-TI-84Plus-CE

This is a day of week calculate tool for the TI-84+ CE.

There are three versions, one of them is written in TI-BASIC and therefore also compatible with newer OS versions, the other is written in ICE and the last one is a resized or 'lite' version of the TI-BASIC version.

why is this different from the standard DayofWk( command?

The standard DayofWk( command calculates all dates using the formula for the Gregorian calendar. This is for most dates just fine, but if you want to know what day of week it was on a date when they still used the Julian calendar DayofWk( won't give you the correct day. For that reason I've made this program, where you can set the date your country switched to the Gregorian calendar manually. The program will then calculate the day of week for any date you give, for your country.

How to send the program to your calculator?

You can easily send the program to your calculator using TiLP or TI-connect CE. Once you've sent it to your calculator there are two possible options to run the program, for the ICE version:
-If the OS of your calculator is 5.5 or higher, then you should run the program via Cesium, or use asmhook.
-If the OS of your calculator is 5.4 or below, you can just run the program via the [prgm] menu.
For the TI-BASIC versions:
-Just run the program via the [prgm] menu

How do I use this program?

For the default versions:

Once you open the program you can press:
-[2nd] to go to the settings
-[enter] to calculate the day of week
-[clear] to exit
-[mode] to see what version you have

For the 'lite' version:

The first time you open the program you'll have to enter when the calendar changed for your country and what date format you want to use.
Then you will be asked the date you want to calculate and it's displayed.
The next time you open the program you can directly input the date.

What are the settings?

There are two different settings:
-On what date your country switched to the Gregorian calendar
-If you want the dates in YYYY-MM-DD, MM-DD-YYYY or DD-MM-YYYY
These settings are all stored in appvars if you use the ICE version, and they're stored in matrix [H] if you use the TI-BASIC version.

Once you press [enter] in the first screen, you'll be asked the year, month and day in the order you selected in the settings. The default setting is that you see the notation: YYYY/MM/DD.

Will the program be 100% correct?

Well, it is very difficult to say if it is correct, but as far as I've tested, all dates were correct.

How does the program calculate the day of the week?

This program makes use of the Zellers Congruence to calculate the day of the week. This is are two formulas that can be used to calculate the day of week in the Gregorian and Julian calendar. If you want to know more, I reccomend reading the wikipedia page about it: https://en.wikipedia.org/wiki/Zeller%27s_congruence

The default setting for the date notation is: YYYY/MM/DD.
The default setting for the calendar switch is: 4 October 1582.

IMPORTANT NOTES:

-If you live in Sweden, the dates that the Swedish calendar was used (from 1700 till 1753) will NOT be correct.
-If your country used another calendar than the Julian before changing to Gregorian, you should input in the settings the first gregorian date
-If your country used another calendar than the Julian before changing to Gregorian, you can ONLY calculate dates from 14 days after the calendar change and later.
-If you live in Turkey, you should input as calendar change 1 Januari 1926, since that's when they also took the current year counting.


If you find any bugs, feel free to contact me via: privacy_dragon@tutanota.com or create a issue

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this is a day of week calculate tool for the TI-84+ CE that works correctly, even with dates of before the change to the Gregorian calendar. So it works for both the Julian dates and the Gregorian dates

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