(HP-67/97) Planetary Ephemeris
09-13-2015, 11:10 AM
Post: #1
 Thomas Klemm Senior Member Posts: 1,449 Joined: Dec 2013
(HP-67/97) Planetary Ephemeris
From Programming Handheld Calculators by Paul Lutus.

09-20-2015, 08:53 PM (This post was last modified: 09-20-2015 08:58 PM by Dieter.)
Post: #2
 Dieter Senior Member Posts: 2,401 Joined: Dec 2013
RE: (HP-67/97) Planetary Ephemeris
(09-13-2015 11:10 AM)Thomas Klemm Wrote:  From Programming Handheld Calculators by Paul Lutus.

Could you take a look at line 101? The code there is...

Code:
 97 1  98 RCL (i)  99 FRAC 100 STO 3 101 - 102 1 103 RCL 3 104 - 105 /

This calculates (1–R3)/(1–R3) which is always 1. ;-)
I think line 101 should read "+".

I also assume that "lbl A", "lbl B", "lbl C" and "lbl D" in the user instructions (table 3) are supposed to mean simply "A", "B", "C" and "D".
Typing a label instruction in run mode does not do anything. ;-)

Finally there are some "TF" commands. This was a HP65 instruction. On the HP67/97 testing flags is done with the "F?" command. I hope the program considers the 67/97's special behaviour of Flag 2 tests. ;-)

Dieter
09-20-2015, 09:47 PM
Post: #3
 Thomas Klemm Senior Member Posts: 1,449 Joined: Dec 2013
RE: (HP-67/97) Planetary Ephemeris
(09-20-2015 08:53 PM)Dieter Wrote:  Could you take a look at line 101? The code there is...

Code:
 97 1  98 RCL (i)  99 FRAC 100 STO 3 101 - 102 1 103 RCL 3 104 - 105 /

This calculates (1–R3)/(1–R3) which is always 1. ;-)
I think line 101 should read "+".

It appears that these lines calculate $$\frac{1+e}{1-e}$$ of the formula in the mentioned article.

Quote:I also assume that "lbl A", "lbl B", "lbl C" and "lbl D" in the user instructions (table 3) are supposed to mean simply "A", "B", "C" and "D".
Typing a label instruction in run mode does not do anything. ;-)

Finally there are some "TF" commands. This was a HP65 instruction. On the HP67/97 testing flags is done with the "F?" command. I hope the program considers the 67/97's special behaviour of Flag 2 tests. ;-)

I haven't tested this program. But Paul Lutus mentioned that there were errors both in the listing and the data:
Quote:As with the solar position program, the article's publication created a lot of correspondence, including inquiries from JPL and its consultants asking about mathematical details and correcting some errors in the original published data tables (example).

It would be cool if we could make this program run correctly.

Cheers
Thomas
09-20-2015, 10:00 PM
Post: #4
 Dieter Senior Member Posts: 2,401 Joined: Dec 2013
RE: (HP-67/97) Planetary Ephemeris
(09-20-2015 09:47 PM)Thomas Klemm Wrote:  It appears that these lines calculate $$\frac{1+e}{1-e}$$ of the formula in the mentioned article.

Yes, that's why I think there must be a "+" instead of a "–" in line 101.

(09-20-2015 09:47 PM)Thomas Klemm Wrote:  I haven't tested this program. But Paul Lutus mentioned that there were errors both in the listing and the data:
...
It would be cool if we could make this program run correctly.

This should be no problem with a simple image editor. ;-)
Or maybe a HP97 user provides a (corrected) printed listing.

I do not know anything about astronomy, so maybe someone who is more into this could check the program as well as its data set, and post some results it returns. Or those it should return. ;-)

Dieter
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