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These are the tests which can give you quite a good profile and accuracy rating for your financial calculator. Any more contributions and confirmation are very much appreciated and I will update the swissmicros page (though I may need to move it off there at some point). ``` | # | Ref | N | I%YR | PV | PMT | FV | P/YR | Mode | |----|------------|--------------|-----------|----------|--------------|-----------|------|-------| | 1 | DM | 38 x 12 | 5.25% | 270'000 | ? | 0 | 12 | end | | 1b | DM | 38 x 12 | ? | 270'000 | -14'584/12 | 0 | 12 | end | | 2 | SlideRule | 360 | 15% → 12% | 100'000 | ?-? | 0 | 12 | end | | 3 | Kahan 1983 | 60x60x24x365 | 10% | 0 | -0.01 | ? | =N | end | | 4 | DM | 480 | 0 → ? | 100'000 | ?→ PMT | 0 | 12 | end | | 5 | Dieter | 10 | ? | 50 | -30 | 400 | 1 | end | | 6 | Dieter | 10 | ? | 50 | -30 | 80 | 1 | end | | 7 | A Chan | 10 | ? | -100 | 10 | 1e-10 | 12 | end | | 8 | Miguel | 32 | ? | -999'999 | 0 | 1e6 | 1 | end | | 9 | DM | ? | 25 | 100000 | -2083.333334 | 0 | 12 | end | | 10 | DM | ? | 25 | 100000 | -2040.816327 | 0 | 12 | begin | | 11 | robve | 60x24x365 | 1/6% → ? | 0 | -0.01 | ?→ FV | =N | end | | 12 | robve | 40 | ? → I%YR | 900 | -400 | -1000 → ? | 1 | begin |

2: https://www.hpmuseum.org/forum/thread-20707.html 3: https://www.hpmuseum.org/forum/thread-1012.html 5, 6: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv021.cgi?read=234439 7: https://www.hpmuseum.org/forum/thread-18359-post-161549.html#pid161549 8: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv017.cgi?read=120592 11, 12: https://www.hpmuseum.org/forum/thread-16565-page-2.html ```

Puzzle 2 is from here, and needs you to calculate PMT given n = 360, I%YR = 15%, PV = 100'000, FV = 0, then calculate PMT, but with I%YR = 12%. Subtract the two results, and put that back into PMT, then change n = 36 and I%YR = 15% again, and calculate PV.

Puzzle 3: you may need to divide I%PY by N depending on how your calculator handles i vs I%YR and what the limit is on P/YR.

Puzzle 4 needs you to calculate PMT first given I%YR = 0, then re-input this back into PMT and calculate I%YR. On the HP-12c this is best done by pressing x<>y twice before putting back into PMT.

Puzzle 11: calculate for FV first, re-input back to FV and compute I%YR.

Puzzle 12: calculate for i first, re-input back into i and compute FV.

The other puzzles are just a solve for '?'.

They can be a bit confusing, so I also did a couple of videos here and here solving them on a DM-42 and HP-12c.

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The Strange Case of The Rogue HP-12c
  • Really glad you enjoyed it!! It's a very very small niche of people I think.

    Totally would love to work on an edge cases database! It is no secret (posted on swiss micros forum), but I can do a submission here if that works?

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    Sea, beer and a calculator.
  • Yes, looks like coated aluminium - not unlike a can but a little thicker and with no sharp edges. I've not seen these before but I think they are disposable/recyclable - i.e. a replacement for a plastic cup and far more pleasant to drink from. I took mine home as a souvenir, but I have had to unsquish it today taking it out of hold luggage.

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    Sea, beer and a calculator.
  • Yes, in fact before I got my DM42 I had one holiday where we had no internet access in the evenings and as the children were small and slept early, I didn't have much to do but I was able to learn a lot about using and programming free42.

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    Sea, beer and a calculator.
  • You do have to remind yourself at the beginning that you're using RPN, but after a while it feels a bit like working sums out on paper.

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  • A random shot of my calculator 5000 miles from home while I enjoy a beer near the Pacific. We had been discussing how much water was on earth and what size of a ball it would make. I have no affiliation with the brewing company so apologies for the product placement.

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    Which key mapping(s) have you made that you think other Neovim users might like?
  • Just to clarify - means two taps of the esc key in succession will clear highlighting (ps I'm curious how other people do it!).

    nmap <esc><esc> :noh<return>

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    Which key mapping(s) have you made that you think other Neovim users might like?
  • Yes, I also have caps mapped to esc, but done in keyboard firmware so that holding it functions as ctrl.

    In neovim I have two escapes mapped to :noh

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    HP-12c Platinum
  • Yeah, I think they need to tune their nibs before they let them out. No such thing as too much flow - just too little paper.

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    HP-12c Platinum
  • That's lovely - these calculators are very 'dad' style to me also (though my dad had a 70s style Casio). There's something about the voyager HP calculators with their landscape format - they are really satisfying to use, I can see why he kept it on him!

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    HP-12c Platinum
  • It's a Stilform fountain pen. They are a recent make using machined parts and bock nibs with a nifty magnetic cap. I'm having slight issues with the bock nibs though - they are going to need a bit more work to keep the flow how I like it.

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    HP-12c Platinum
  • I always thought of financial calculators as a sort of gelded single-function function machine and I didn't really get them. However, that would ignore the vast number of models available from HP, and that their second ever pocket calculator was a financial one. It turns out that solving the time value of money equation is non-trivial, and the work done on that probably paved the way for calculators with a solver.

    The other thing I didn't appreciate until I had to use it, is that the interface of the 12c - with the 5 buttons in the top left for n, i, pv, pmt and fv is peak user interface. Press once to input data, but a second consecutive press of these buttons will trigger the solve and drop the result into x. It's perfect, and means you can solve and use all the calculator functions and stack continuously. Most modern methods use a table, which is hard to extract and input information from the calculator.

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  • HP's most accurate financial calculator, oddly enough, and despite only returning the ceiling of solve-for-n.

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    Psion Series 3
  • These were such great machines, so far ahead of their time. I had a 3a, and nothing has beaten the Agenda program on it. I think part of the reason it was so good was that it wasn't a touch screen and the keyboard control was so well thought out, especially tab to bring up a monthly calendar. And what modern calendar has a year view that is useful?

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    Casio BN-20
  • That is a well-filled pen! It looks like others have said this, but nothing has ever beaten my 90s PDA for organising my life.

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    SM DM42
  • The Asvine is a poor man's ASC, but it is beautiful and arguably the difference saved covers the DM42. But that's me jumping through mental hoops to justify a purchase of course.

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    Wes Streeting announces independent probe into performance of NHS
  • Please don't tell me what I need to learn about before arguing, especially if your point doesn't directly address mine. The two views are:

    1. A different system will result in a better service
    2. More resources will result in a better service

    I know which of those two I would investigate first.

    Also an observation about language and how we frame things - "strategic excess" of the German system == "inefficiency" in the NHS. I'm not arguing one way or another here, but the way we use language can greatly affect the public discourse on the subject.

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    Wes Streeting announces independent probe into performance of NHS
  • Had a quick look on Wikipedia - Germany spends $8011/capita versus $5493 in the UK, a 45.8% higher amount. Rather than suggest we pass our money through a profit-focussed middleman, like we do for car insurance, why don't we try matching our spending first?

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  • First post on Lemmy, and i see you like pens too :)

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