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Re: Conversion of ISO Date-stamps into Weekday Numbers

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  Re: Conversion of ISO Date-stamps into Weekday Numbers lachman@ebony.ppc.ubc.ca (Milton Lachman) - 2011-03-15 10:26 +0000
    Re: Conversion of ISO Date-stamps into Weekday Numbers lachman@ebony.ppc.ubc.ca (Milton Lachman) - 2011-03-15 12:00 +0000
    Re: Conversion of ISO Date-stamps into Weekday Numbers "Brian Gaff" <Briang1@blueyonder.co.uk> - 2011-03-16 10:15 +0000
      Re: Conversion of ISO Date-stamps into Weekday Numbers spike1@freenet.co.uk - 2011-03-16 12:26 +0000
        Re: Conversion of ISO Date-stamps into Weekday Numbers "Brian Gaff" <Briang1@blueyonder.co.uk> - 2011-03-17 08:36 +0000
          Re: Conversion of ISO Date-stamps into Weekday Numbers spike1@freenet.co.uk - 2011-03-17 09:36 +0000
            Re: Conversion of ISO Date-stamps into Weekday Numbers korax1214 <korax1214@gmail.com> - 2011-03-17 16:15 -0700
              Re: Conversion of ISO Date-stamps into Weekday Numbers jgharston <jgh@arcade.demon.co.uk> - 2011-03-17 17:49 -0700
                Re: Conversion of ISO Date-stamps into Weekday Numbers "Brian Gaff" <Briang1@blueyonder.co.uk> - 2011-03-18 07:10 +0000
          Re: Conversion of ISO Date-stamps into Weekday Numbers lachman@ebony.ppc.ubc.ca (Milton Lachman) - 2011-03-23 18:06 +0000
            Re: Conversion of ISO Date-stamps into Weekday Numbers jgharston <jgh@arcade.demon.co.uk> - 2011-03-24 16:04 -0700
              Re: Conversion of ISO Date-stamps into Weekday Numbers lachman@ebony.ppc.ubc.ca (Milton Lachman) - 2011-03-27 16:48 +0000
          Re: Conversion of ISO Date-stamps into Weekday Numbers lachman@ebony.ppc.ubc.ca (Milton Lachman) - 2011-03-23 21:32 +0000

#70 — Re: Conversion of ISO Date-stamps into Weekday Numbers

  HOW TO COMPUTE THE DAY OF THE WEEK FOR DATE-STAMPS 10010101 TO 99991231
     - using Hans Lachman's Method of Congruence as generalised below -


Strictly adhering to Lachman's Maxim (Complexity is a diseconomy of scale),
 this method is designed to run superbly as a stand-alone subroutine, when
 the most basic of computer is the only resource--meaning no values needed
 from user tables or system calls, and no floating point variables.

 Although using a processor more sophisticated than found on four-function
 calculators, this method is simpler to execute than Hans' original Method
 of Congruence needing manipulation of data by numerically competent users.
 It succeeds where other Methods do not when computing the day of the week
 even on lowly Sinclair ZX BASIC: having no need of extra instructions for
 data stored in tables as in Babwani's Method nor for redundant operations
 as in Zeller's or Tondering's--nor even a C compiler running on a bloated
 development system as in Mike Keith's-- yet doing more in under 12 lines.

Given:

 D$(8) as a Date-stamp YYYYMMDD in basic ISO format,
 N%    as its amount of shifting,
    &  F% as a false flag for non-Gregorian calendars:
 300    0    Julian (historical)
 301    0    Byzantine
 325    0    Old-Style
 300   50    Gregorian (historical);
 K%    as an addend (19300 for integer arithmetic)
 X%    as a multiplier (256 for integer arithmetic)

the Sinclair BASIC subroutine below is to compute:

 y%    as the Year
 m%    as the month
 m$    whereby m$(2TO3)=MonthIndex
 d%    as the day's number within the month
 i%    as an increment to K%
 w%    as the ISO-compatible number of the corresponding weekday:
          Sun=0  Mon=1  Tue=2  Wed=3  Thu=4  Fri=5  Sat=6


 REM Step 0 - isolate components of & offset the Date-stamp:
 LET y%=D$(1TO4) : m%=D$(5TO6) : d%=D$(7TO8) : s$=D$-N% : i%=F%+F%
 IF N%=301 THEN
    IF m%>8 THEN LET s$(1TO4)=s$(1TO4)-1
    IF s$(5TO6)<6 THEN LET i%=100
 END IF
 IF N%=325 THEN
    IF s$(5TO8)>9775 THEN LET i%=100
    IF s$(5TO8)>9975 THEN LET s$(1TO4)=s$(1TO4)+1
 END IF

 REM Step 1 - compute the MonthIndex:
 LET m$=m%*X% + K% + i%

 REM Step 2 - compute the weekday-number:
 LET w%=(s$(1TO4)DIV4 + y% + m$(2TO3) + d% + F%*s$(1TO2)DIV8 + F%)MOD7    


 The subroutine is streamlined such that parameters are to be passed in
 proper format. For example, one must pass a flag of 50 for Gregorian
 dates as of 15.oct.1582 A.D, & 0 for non-Gregorian as of 1.jan.1001:
 A.D. for Julian & Old Style calendars; & A.M. for Byzantine calendars.
 The subroutine thereby gives compleat, valid, historical continuity of
 date-stamp conversion until 31.dec.9999 in the relevant epoch.

 Because of its initial overlap with the historical year, a 93 addend is
 to apply till December 31st. From January 1st, a 94 addend applies till
 the end of the Old Style year on March 24th or also till the end of the
 Byzantine year on August 31st. Month-numbers remain defined in terms of
 the historical year for both (as for calendars where N%=300).


--

REFERENCES             http://oz.ccnet.us/dayofweek/
                http://www.guernsey.net/~sgibbs/roman.html
           http://en.wikipedia.org/wiki/Zeller%27s_congruence
  http://www.tondering.dk/claus/cal/node3.html#SECTION00360000000000000000
babwani-congruence.blogspot.com/search/label/Frequently%20AskeD$20Questions

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#72

>
> Because of its initial overlap with the historical year, a 93 addend is
> to apply till December 31st. From January 1st, a 94 addend applies till
. . .
>REFERENCES             http://oz.ccnet.us/dayofweek/
. . .
The addends should be 19300 & 19400 for integer arithmetic,
rather than those for a calculator as used in the 1st reference.
Also, here's the missing link to Mike Keith's method:
            http://www.merlyn.demon.co.uk/zel-like.htm#Keith

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#73

Thats no zx basic I know.

Brian

-- 
Brian Gaff - briang1@blueyonder.co.uk
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Milton Lachman" <lachman@ebony.ppc.ubc.ca> wrote in message 
news:ilnet7$svj$1@droog.sdf-eu.org...
>  HOW TO COMPUTE THE DAY OF THE WEEK FOR DATE-STAMPS 10010101 TO 99991231
>     - using Hans Lachman's Method of Congruence as generalised below -
>
>
> Strictly adhering to Lachman's Maxim (Complexity is a diseconomy of 
> scale),
> this method is designed to run superbly as a stand-alone subroutine, when
> the most basic of computer is the only resource--meaning no values needed
> from user tables or system calls, and no floating point variables.
>
> Although using a processor more sophisticated than found on four-function
> calculators, this method is simpler to execute than Hans' original Method
> of Congruence needing manipulation of data by numerically competent users.
> It succeeds where other Methods do not when computing the day of the week
> even on lowly Sinclair ZX BASIC: having no need of extra instructions for
> data stored in tables as in Babwani's Method nor for redundant operations
> as in Zeller's or Tondering's--nor even a C compiler running on a bloated
> development system as in Mike Keith's-- yet doing more in under 12 lines.
>
> Given:
>
> D$(8) as a Date-stamp YYYYMMDD in basic ISO format,
> N%    as its amount of shifting,
>    &  F% as a false flag for non-Gregorian calendars:
> 300    0    Julian (historical)
> 301    0    Byzantine
> 325    0    Old-Style
> 300   50    Gregorian (historical);
> K%    as an addend (19300 for integer arithmetic)
> X%    as a multiplier (256 for integer arithmetic)
>
> the Sinclair BASIC subroutine below is to compute:
>
> y%    as the Year
> m%    as the month
> m$    whereby m$(2TO3)=MonthIndex
> d%    as the day's number within the month
> i%    as an increment to K%
> w%    as the ISO-compatible number of the corresponding weekday:
>          Sun=0  Mon=1  Tue=2  Wed=3  Thu=4  Fri=5  Sat=6
>
>
> REM Step 0 - isolate components of & offset the Date-stamp:
> LET y%=D$(1TO4) : m%=D$(5TO6) : d%=D$(7TO8) : s$=D$-N% : i%=F%+F%
> IF N%=301 THEN
>    IF m%>8 THEN LET s$(1TO4)=s$(1TO4)-1
>    IF s$(5TO6)<6 THEN LET i%=100
> END IF
> IF N%=325 THEN
>    IF s$(5TO8)>9775 THEN LET i%=100
>    IF s$(5TO8)>9975 THEN LET s$(1TO4)=s$(1TO4)+1
> END IF
>
> REM Step 1 - compute the MonthIndex:
> LET m$=m%*X% + K% + i%
>
> REM Step 2 - compute the weekday-number:
> LET w%=(s$(1TO4)DIV4 + y% + m$(2TO3) + d% + F%*s$(1TO2)DIV8 + F%)MOD7
>
>
> The subroutine is streamlined such that parameters are to be passed in
> proper format. For example, one must pass a flag of 50 for Gregorian
> dates as of 15.oct.1582 A.D, & 0 for non-Gregorian as of 1.jan.1001:
> A.D. for Julian & Old Style calendars; & A.M. for Byzantine calendars.
> The subroutine thereby gives compleat, valid, historical continuity of
> date-stamp conversion until 31.dec.9999 in the relevant epoch.
>
> Because of its initial overlap with the historical year, a 93 addend is
> to apply till December 31st. From January 1st, a 94 addend applies till
> the end of the Old Style year on March 24th or also till the end of the
> Byzantine year on August 31st. Month-numbers remain defined in terms of
> the historical year for both (as for calendars where N%=300).
>
>
> --
>
> REFERENCES             http://oz.ccnet.us/dayofweek/
>                http://www.guernsey.net/~sgibbs/roman.html
>           http://en.wikipedia.org/wiki/Zeller%27s_congruence
>  http://www.tondering.dk/claus/cal/node3.html#SECTION00360000000000000000
> babwani-congruence.blogspot.com/search/label/Frequently%20AskeD$20Questions
>
> 

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#74

And verily, didst Brian Gaff <Briang1@blueyonder.co.uk> hastily babble thusly:
> Thats no zx basic I know.

I doubt he's even seen a sinclair machine.
-- 
|                          |What to do if you find yourself stuck in a crack|
|  spike1@freenet.co.uk    |in the ground beneath a giant boulder, which you|
|                          |can't move, with no hope of rescue.             |
|  Andrew Halliwell BSc    |Consider how lucky you are that life has been   |
|           in             |good to you so far...                           |
|    Computer Science      |   -The BOOK, Hitch-hiker's guide to the galaxy.|

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#75

I was just trying to figure out what the point of posting it here actually 
was. There are lots of bits of software to work out dates after all, it was 
one of the first things we all wrote and used in those early days.
 Plotting bio rhythms and making appointment books etc.

Brian

-- 
Brian Gaff - briang1@blueyonder.co.uk
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
<spike1@freenet.co.uk> wrote in message 
news:esm658-5lc.ln1@librarian.sky.com...
> And verily, didst Brian Gaff <Briang1@blueyonder.co.uk> hastily babble 
> thusly:
>> Thats no zx basic I know.
>
> I doubt he's even seen a sinclair machine.
> -- 
> |                          |What to do if you find yourself stuck in a 
> crack|
> |  spike1@freenet.co.uk    |in the ground beneath a giant boulder, which 
> you|
> |                          |can't move, with no hope of rescue. 
> |
> |  Andrew Halliwell BSc    |Consider how lucky you are that life has been 
> |
> |           in             |good to you so far... 
> |
> |    Computer Science      |   -The BOOK, Hitch-hiker's guide to the 
> galaxy.| 

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#76

Someone with too much ego and not enough ability to filter what's
appropriate for what group? Look at me! I'm posting something! bow down to
my magnificence! What do you mean it's not sinclair BASIC? what does that
matter? it was posted by me! MEMEME!!

etc.

And verily, didst Brian Gaff <Briang1@blueyonder.co.uk> hastily babble thusly:
> I was just trying to figure out what the point of posting it here actually 
> was. There are lots of bits of software to work out dates after all, it was 
> one of the first things we all wrote and used in those early days.
> Plotting bio rhythms and making appointment books etc.

-- 
|   spike1@freenet.co.uk   |   Windows95 (noun): 32 bit extensions and a    |
|                          | graphical shell for a 16 bit patch to an 8 bit |
|   Andrew Halliwell BSc   | operating system originally  coded for a 4 bit |
|            in            |microprocessor, written by a 2 bit company, that|
|     Computer Science     |        can't stand 1 bit of competition.       |

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#78

You should see the state alt.games.mame is currently in, due to an
egomaniacal (and extremely rude) idiot who, amongst other things,
reckons he knows better than anyone else (including people who have
been there for *years*) what is and isn't acceptable on that group.

Of course, having been there about two months now, by now he's talking
solely to himself, everyone else having killfiled him. :-)

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#79

  REM FNDate_DayOfWeek(day%,month%,year%) - return day of week for
supplied date
  REM                                       1=Sunday, 7=Saturday
  REM
--------------------------------------------------------------------------
  :
  DEFFNDate_DayOfWeek(d%,m%,y%):y%=y%MOD400
  =(y%*365.25+m%*30+d%+VALMID$("120112234455",m%,1)+(y%MOD4)=0)-((y
%-1)DIV100)-(m%>2AND((y%MOD4)=0AND(y%MOD100)<>0ORy%=0))+3)MOD7+1

Conversion to Spectrum Basic is left as an exercise for the reader.

JGH - mdfs.net/BLib

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#82

With due respect, that is not what you originally said.
 I'd suggest that the whole point is that this is a Sinclair group, and one 
would expect it to contain information that was directly usable on said 
machines.
 The string slicing, for example  is much more logical in zx, not using 
these crazy  mid$ rubbish. and what are oll those percent signs about.
 Why use endif when zx basic can do computed gosubsa nd gotos?

Brian

-- 
Brian Gaff....Note, this account does not accept Bcc: email.
 graphics are great, but the blind can't hear them
Email: briang1@blueyonder.co.uk
______________________________________________________________________________________________________________


"jgharston" <jgh@arcade.demon.co.uk> wrote in message 
news:b5c1939b-bab7-42e8-ad15-fdd34f600e9c@x18g2000yqe.googlegroups.com...
>  REM FNDate_DayOfWeek(day%,month%,year%) - return day of week for
> supplied date
>  REM                                       1=Sunday, 7=Saturday
>  REM
> --------------------------------------------------------------------------
>  :
>  DEFFNDate_DayOfWeek(d%,m%,y%):y%=y%MOD400
>  =(y%*365.25+m%*30+d%+VALMID$("120112234455",m%,1)+(y%MOD4)=0)-((y
> %-1)DIV100)-(m%>2AND((y%MOD4)=0AND(y%MOD100)<>0ORy%=0))+3)MOD7+1
>
> Conversion to Spectrum Basic is left as an exercise for the reader.
>
> JGH - mdfs.net/BLib 

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#100

Brian Gaff - briang1@blueyonder.co.uk wrote
><spike1@freenet.co.uk> wrote in message
>> And verily, didst Brian Gaff <Briang1@blueyonder.co.uk> hastily babble
>> thusly:
>>> Thats no zx basic I know.
>>
>> I doubt he's even seen a sinclair machine.
>
>I was just trying to figure out what the point of posting it here actually
>was.

ZX BASIC was on my 1st Sinclair machine, which I had bought instead
of a programmable calculator to crunch lab data. But that was too  
long ago for me to remember 'computed gosubs'. I soon upgraded to a
QL. So I posted a simplified superBASIC routine, w/the expectation 
that it could easily be adapted to ZX BASIC if need be, including  
the END IFs & the integer variables ending in %. In any case, the  
routine is intended to convert NON-Gregorian dates, the kind that  
one will eventually encounter in one's family tree. See my posts on
the soc.genealogy groups for converting Julian & Old-Style dates   
without a computer.

And just in the nick of time for the 1st of April, jgharston's BBC
BASIC routine--esp. having you convert mid$ into spectrum BASIC-- 
is merely a troll.

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#102

Milton Lachman wrote:
> And just in the nick of time for the 1st of April, jgharston's BBC
> BASIC routine--esp. having you convert mid$ into spectrum BASIC--
> is merely a troll.

It wasn't a troll. You provided some code with the unstated
expectation
that people convert it to Spectrum Basic. I provided some prewritten,
tested and extensively-used code with the _explicit_ statement that it
could be converted into Spectrum Basic. I may eventially get around to
doing that conversion myself, but would have no objection to somebody
else doing it before me.

Additionally, my code can actually run on the Spectrum if you choose
to
use BBC BASIC for the Spectrum. mdfs.net/bbcbasic/Spectrum

JGH

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#123

>                Re: Conversion of ISO Date-stamps into Weekday Numbers
>   From: jgharston <jgh@arcade.demon.co.uk>
>Milton Lachman wrote:
>> And just in the nick of time for the 1st of April, jgharston's BBC
>> BASIC routine--esp. having you convert mid$ into spectrum BASIC--
>> is merely a troll.
>
>It wasn't a troll. You provided some code with the unstated expectation
>that people convert it to Spectrum Basic. I provided some prewritten,
>tested and extensively-used code with the _explicit_ statement that it
>could be converted into Spectrum Basic. I may eventially get around to
>doing that conversion myself, but would have no objection to somebody
>else doing it before me.

It's a troll to a certain %, given that your code doesn't convert
ISO date-stamps, as explicitly stated, nor does it convert NON-
Gregorian dates, as also for the original post.
The follow-up to it was posted on the Ides of March on
the Gregorian calendar instead of tomorrow, which is the anniversary
of Julius Caesar's death on his Julian calendar--as egregious a
faux pas as not posting it in ZX BASIC on the 30th anniversary of 
the ZX 81--but this thread started last year as an academic exercise
to exclusively use string variables in superBASIC. Therefore the
thread is meant for the QL, which qualifies as a "sinclair machine"
even if not a ZX 83 officially.

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#101

   From: "Brian Gaff" <Briang1@blueyonder.co.uk>
><spike1@freenet.co.uk> wrote in message
>> And verily, didst Brian Gaff <Briang1@blueyonder.co.uk> hastily babble
>> thusly:
>>> Thats no zx basic I know.
>>
>> I doubt he's even seen a sinclair machine.
>
>I was just trying to figure out what the point of posting it here actually
>was.

The in-house name of the QL was the ZX 83;  I only claimed that
the METHOD was designed with ZX BASIC in mind; and I also dropped
in a claim of "superbly" as a hint that the routine was written in
superBASIC--which qualifies as "Sinclair BASIC" as claimed for the         
routine.

ZX BASIC was on my 1st Sinclair machine, which I had bought instead
of a programmable calculator to crunch lab data. But that was too
long ago for me to remember 'computed gosubs'. I soon upgraded to a
QL. I posted a simplified superBASIC routine, w/the expectation
that it could easily be adapted to ZX BASIC if need be, including
the END IFs & the integer variables ending in %. In any case, the
routine is intended to convert NON-Gregorian dates, the kind that
one will eventually encounter in one's family tree. See my posts on
the soc.genealogy groups for converting Julian & Old-Style dates
without a computer.

And just in the nick of time for the 1st of April, jgharston's BBC
BASIC routine--esp. having you convert mid$ into spectrum BASIC--
is merely a troll.

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