Calculating "Day Of The Week" from a date

hmlittle59 · 2009-07-17 22:22

Hello All,

I did a search and could not find any CODE on this forum. Does anyone know of any PBASIC code (BS2xx) that can do this? I've down loaded the Zeller's info from Google and working on my own. Thanks.

I'll search Google for some BASIC Code.

thanks again

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I'M STILL LEARNING SO MUCH...BUT STILL KNOW SO LITTLE!!!

hmlittle59

CounterRotatingProps · 2009-07-17 23:04

This is probably a good coding exercise - try it and if you can't get it to work, post what you have and we can help you figure it out. How far forward and backward in time does it have to go? - H

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mctrivia · 2009-07-17 23:12

en.wikipedia.org/wiki/Calculating_the_day_of_the_week#An_algorithm_to_calculate_the_day_of_the_week

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xanatos · 2009-07-17 23:20

I have that coded in VBScript if you're interested.· I did it for my calendar manager application I wrote a few years ago.· If you can read VBS, you could probably do the same in PBASIC.· The calculations are pretty basic (no pun intended)....· I got this from the math in an OLD magic/mentalism book, believe it or not.· In "another life" I was a magician and mentalist...·· I hope the code is useful. the variable diffYear is just the 4 digit year to use (2009, 1020, etc).

   ' Here is where we calculate the day of the week from the date 
    ' (Thanks to Corrinda's "13 Steps to Mentalism"!)
   
    Dim whichDay, toChop
   
    whichDay = mid(diffYear,3,2) + int((mid(diffYear,3,2)) / 4) + monthCode + thisDate
    toChop = int(whichDay / 7)
    chopFrom = whichDay / 7
    rawDay = (chopFrom - toChop) * 7
    roundDay = Cint(rawDay)
    whichDay = roundDay - 3 ' -3 = Century Code until 2099 for comp...
    
    if diffMonth < 3 then whichDay = whichDay - leapYear ' Fudge Factor- why dates don't line up?
    
    if whichDay < 0 then whichDay = whichDay + 7
    if whichDay = 0 then
     whichDay = "Saturday"
    elseif whichDay = 1 then
     whichDay = "Sunday"
    elseif whichDay = 2 then
     whichDay = "Monday"
    elseif whichDay = 3 then
     whichDay = "Tuesday"
    elseif whichDay = 4 then
     whichDay = "Wednesday"
    elseif whichDay = 5 then
     whichDay = "Thursday"
    elseif whichDay = 6 then
     whichDay = "Friday"
    end if

mctrivia · 2009-07-17 23:58

spin code *untested
should be accurate to 2099

DAT
MTable       long      0, 2678400,5097600,7776000,10368000,13046400,15638400,18316800,20995200,23587200,26265600,28857600
  

PUB datetonum(year,month,day,hour,minute,sec) | time 'year 2 digits, month 0-11, day 0-30, hour 0-23, min 0-59, sec 0-59
  time:=31536000*year+86400*(year/4)+Long[noparse][[/noparse]@MTable][noparse][[/noparse]month]+86400*day+hour*3600+minute*60+sec
  if (year//4) & (month>1)
    time+=86400
  return time

PUB dayofweek(num) | time 'sun=0, mon=1...
  time:=(6+(num/86400))//7
  return time

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propmod_us and propmod_1x1 are in stock. Only $30. PCB available for $5

Want to make projects and have Gadget Gangster sell them for you? propmod-us_ps_sd and propmod-1x1 are now available for use in your Gadget Gangster Projects.

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hmlittle59 · 2009-07-18 00:38

Hello All,

Thanks to all that replied, I'm already using the DS1302 and wanted to CODE it in. I looked in the Editor Help file and found the (//) command for Modulus. I'll be using the examples and figure it out...Thanks again

Hmlittle59

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I'M STILL LEARNING SO MUCH...BUT STILL KNOW SO LITTLE!!!

hmlittle59

Peter Verkaik · 2009-07-18 13:07

'dy is 1..31
'mn is 1..12
'yr is >= 1900
IF mn < 3 then· 'Jan & Feb = 13 & 14 preceding year
· mn = mn + 12
· yr = yr - 1
ENDIF
· weekday = (dy + 2*mn + (3*(mn+1)/5) + yr + (yr/4) - (yr/100) + (yr/400) + 1) // 7· '0=sunday

regards peter

Chris Savage · 2009-07-18 18:35

Hmlittle,

The DS1302 already keeps track of the day of the week. Was there something outside of that you were trying to do?

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Chris Savage
Parallax Engineering

hmlittle59 · 2009-07-18 20:08

Hello Chris,

I just wanted to learn to do it within my program without knowing?

Thanks Peter and to All

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I'M STILL LEARNING SO MUCH...BUT STILL KNOW SO LITTLE!!!

hmlittle59

Post Edited (hmlittle59) : 7/18/2009 8:34:58 PM GMT

Chris Savage · 2009-07-18 20:51

Ok, that's cool. I was just curious.

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Chris Savage
Parallax Engineering

mctrivia · 2009-07-18 23:49

i wish there was a RTC that used EPOCH time(or my equivalent starting jan 1st, 2000)

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PJAllen · 2009-07-19 20:43

http://www.terra.es/personal2/grimmer/

·

Tracy Allen · 2009-07-20 00:14

There is PBASIC code posted at this link on JulianDateTime.

RTC chips do keep a cyclic count of 7 days, but you have to initialize it to the day of week scheme you want linked to the calendar day.

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Tracy Allen
www.emesystems.com

hmlittle59 · 2009-07-20 22:04

Hello Peter,
I tried this code and I seem to be having some problems getting it to work correctly, could you help me get it working please?
thanks to all that can help

'   {$STAMP BS2e}
'   {$PBASIC 2.5}
' -----[noparse][[/noparse] I/O Definitions ]-------------------------------------------------
  DOW                VAR     Byte
  Month               VAR     Byte
  Day                  VAR     Byte
  Year                 VAR     Word
'***********************************************************************************
'                  Set Default Month/Date/Year/Day/Time..
'***********************************************************************************

  Day               =   20            ' 01st....31st
  Month            =   07            ' Jan..to..Dec
  Year              =   09            ' 01...99

 IF month < 3 THEN
  month =  month + 12
  year =  year - 1
 ENDIF

DOW = (Day+2*month+(3*(month +1)/5)+year+(year/4)-(year/100)+(year/400) + 1) // 7

DEBUG "Date of Today   ", DEC2 day  ,CR
DEBUG "Month of Year   ", DEC2 Month,CR
DEBUG "What's the Year ", DEC2 year ,CR
DEBUG "Day of Week     ", DEC2 DOW  ,CR

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I'M STILL LEARNING SO MUCH...BUT STILL KNOW SO LITTLE!!!

hmlittle59

Chris Savage · 2009-07-20 22:08

A note on Tracy's post for anyone not experienced with the DS1302. It does assign a number to the day of the week, but unlike the other registers it doesn't count 0 as a valid day, only 1-7.

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Chris Savage
Parallax Engineering

Calculating "Day Of The Week" from a date

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