Easter Formula

[Gunther]

Calendar questions are not simple, as they are closely entangled with both astronomical phenomena and religious circumstances. The EASTER.EXE program calculates the correct Easter date for a given
year after 1582. It is written with PB 3.5; the Easter calculation is done in assembly language with JWASM for DOS.

The EASTER.PDF file contains some background information. Hopefully, these are comprehensible. I've made every effort to be factually correct. But the subject is really difficult and I didn't want to go into
too much detail. Did I succeed in doing that? I don't know. Some feedback on this would be nice.

The output of the program looks like that:

Code Select Expand


Application EASTER:
===================

This program performs astronomical  and calendar calculations. First,
the date of Easter for an arbitrary year after 1582. The year must be
entered as an integer, otherwise the result will be nonsense.

Easter Sunday for the chosen year: April 17, 2022

Please, press any key to end the application...

In the text EASTER.PDF are mentioned boundary cases; these are of course calculated correctly. Here are the results for the lower limit:

• Easter Sunday for the chosen year: March 22, 1818
• Easter Sunday for the chosen year: March 22, 2285

For the upper limit applies:

• Easter Sunday for the chosen year: April 25, 1943
• Easter Sunday for the chosen year: April 25, 2038

The application only needs an 80386 and should therefore run under many DOS configurations. This, of course, must be tested. Any help for this I'm grateful.

[learn64bit]

Win3.1 + MS-DOS5.0 works ok.

[Gunther]

Win3.1 + MS-DOS5.0 works ok.

Thank you for the answer and your help.  Did you also read the background information in EASTER.PDF? Was that helpful?

But allow me to ask you one more question: On which machine are you still running Windows 3.1 -- obviously not 3.11 -- and DOS 5.0? That' s something you really
don't find very often these days.

[HSE]

Hi Gunther!

Very interesting.

Perhaps "However, in that formula" could be better than "However, in this formula", because I was thinking in this program.

I think something is missing in: "avoiding the need for an exception." ( the need ... to prevent known exception ocurrences, exception catch, ¿?)

Regards, HSE.

[Gunther]

HSE,

thank you for your response.   

Perhaps "However, in that formula" could be better than "However, in this formula", because I was thinking in this program.

Is that in EASTER.PDF or in the source code?

I think something is missing in: "avoiding the need for an exception." ( the need ... to prevent known exception ocurrences, exception catch, ¿?)

That's probably correct. The Gaussian Easter formula mentioned in EASTER.PDF can be used in both the Julian and the Gregorian calendar. But there's a price to pay for that.
Although the Gaussian Easter formula elegantly summarizes the Easter algorithm, the specification of the latest Easter Sunday as April 25, contained in two exception rules,
is not captured by the formula itself. In other words: The Gaussian formula needs exceptional rules.

This is not the case with the Easter formula I've been using. However, this formula works only for the Gregorian calendar. Therefore, the program rejects any year before 1583.
Was that your point of critique?

[HSE]

Gunther,

Was that your point of critique?

I think "an exception" or "exceptional rules" is not English Language but jargon. A limited group of persons can understand perfectly what you mean, but not eveybody. It's not my jargon, I can imagine what could be, but perhaps I'm wrong because that is not in the text.

[Gunther]

HSE,

I think "an exception" or "exceptional rules" is not English Language but jargon.

Well, I'm not a native speaker. However, I think exception is anything but jargon or slang. I also think that
the phrase the exception that proves the rule is understood by more than just a  limited group of persons.

But hey, what do I know? How would you formulate it then? No offense intended.

[HSE]

Gunther,

No offense intended.

No problem

How would you formulate it then?

You know exactly what problems calculation of Gauss equation have, perhaps indetermination for some inputs, results are valid for a limited range of inputs. I don't know. Just sound incorrect to say that an equation have exceptions. Equations don't have exceptions.

If intended audience understand what you mean, that is Ok.

[learn64bit]

Gunther,

No, I never saw a real machine running MS-DOSv5 and Win3.1 in my life yet...
I run they in "fake machine", like VMwareWorkstation,VMvirtualBox,PCem,86box,AltairZ80simulator...

[Gunther]

learn64bit,

I run they in "fake machine", like VMwareWorkstation,VMvirtualBox,PCem,86box,AltairZ80simulator...

Ah, a virtual machine. That makes it clear. Where can I find the installation disks?

[FORTRANS]

Hi,

The EASTER.PDF file contains some background information. Hopefully, these are comprehensible. I've made every effort to be factually correct. But the subject is really difficult and I didn't want to go into
too much detail. Did I succeed in doing that? I don't know. Some feedback on this would be nice.

   I think the PDF is well written.  The level of detail is rather good.  Nice use
of the word 'manifold'.  Perhaps the formulas could add information.  But
you include source code and references, and it might be too complicated for
easy reading.  To address HSE's concerns; "avoiding the need for an
exception." could be changed to "without needing a correction."  However,
your wording is perfectly fine.  Unambiguous in its context.  A nice clean
document overall.

   The program runs in Win 2000's NTVDM without problems.

Regards,

Steve N.

[TimoVJL]

Abandoned files

[learn64bit]

Gunther,

https://winworldpc.com

I download MS-Word 97, Word 6.0 for Win, DOSv5.0, Win3.1...Adobe Acrobat Read v3... from this site.

[Gunther]

HSE,
more and more I understand what you mean.

You know exactly what problems calculation of Gauss equation have, ...

But you are on thin ice with this. There are good reasons why it's called Gaussian Easter formula and not Gaussian Easter equation. It's not a classical equation, like the solution formula for quadratic equations.
The Gaussian Easter formula is more an algorithm. Why it was not called Gaussian Easter algorithm, I can speculate only. There is a Gaussian algorithm for solving linear equation systems. Perhaps one wanted
to avoid confusion? Be that as it may, we have to live with the name as it has become established.

Just sound incorrect to say that an equation have exceptions. Equations don't have exceptions.

However, an algorithm may very well have exceptions. And by the way, there are many equations that have also exceptions. Here's an example. You can apply many mathematical operations to an equation as long
as it's done on both sides. But division by 0 is an exception in any case.

[Gunther]

TimoVJL,

Abandoned files

learn64bit,

https://winworldpc.com

these are both interesting sites. But is downloading from there legal?