could not calculate i (2)

Things that aren't right, that are in the queue to be fixed... along with workarounds.
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jaimer7
Posts: 2
Joined: Sun Feb 01, 2009 6:09 pm

could not calculate i (2)

Post by jaimer7 » Sun Feb 01, 2009 6:29 pm

I got the above-mentioned error message when I was trying out the HP-12E (which I purchased a few days ago) on an example problem found in the HP12C owner's handbook and problem-solving guide.

Here are the details of the example problem in the HP12C handbook.

An investor wishes to purchase a $100,000 mortgage taken out at 9% for 21 years. Since the mortgage was issued, 42 montly payments have been made. What would the annual yield if the purchase price of the mortgage is $79,000? (Since PMT was not given, it must be calculated).

The HP12c handbook gives 11.68% annual yield, I solved that problem using my HP17B (physical calculator) and got 11.68% annual yield. My HP12c ROM emulator in my PC also gave the same result.

jaimer7

Xeno
Posts: 55
Joined: Sat Oct 25, 2008 4:15 pm

Re: could not calculate i (2)

Post by Xeno » Sun Feb 01, 2009 7:13 pm

Hello jaimer7

I can replicate your results on a 12C emulator and a 17Bii but on the 12E I got 11.68 also, not any sort of error.

You evidently have experience with financial calculators so forgive me for checking a couple of basic things, but were you in TVM mode (Blue 8), End mode (tap Begin indicator to see End display if necessary) and were all operations the same?

At the point where you tried to calculate i, what were the contents of the financial registers, as visible in the small display line above the financial keys?
I would expect you to see 210, i, -79000, 884.581, 0 with i becoming 0.97 when calculated and 11.68 when multiplied by twelve. The signs of the PV and PMT could be reversed of course.

HTH
David

theDev
Posts: 240
Joined: Mon Aug 04, 2008 8:58 pm

Re: could not calculate i (2)

Post by theDev » Sun Feb 01, 2009 8:11 pm

jamier...

Let me check into this.

Thank you for letting me know, I'll get to the bottom of it.

Kim

theDev
Posts: 240
Joined: Mon Aug 04, 2008 8:58 pm

Re: could not calculate i (2)

Post by theDev » Mon Feb 02, 2009 10:38 am

Jamier:

You are right, and this is a new issue with v1.3.1 -- I am working with Roy to validate the fix. It has to do with seed values sent to the solvers, values that were adjusted in v1.3.1 to make things "better". Obviously that isn't what happened.

As soon as the fix is validated and retested I'll get the update out.

This is very embarrassing and I do humbly apologize.

Kim

Xeno
Posts: 55
Joined: Sat Oct 25, 2008 4:15 pm

Re: could not calculate i (2)

Post by Xeno » Mon Feb 02, 2009 1:32 pm

Now this is very odd. I did not encounter the problem because (as I discover now) I still have v1.3. The store shows 1.3.1 but does not describe there being an update for me.

I think I know the source of the technical glitch and might need to talk to Apple first before bothering Kim with it.

Xeno
Posts: 55
Joined: Sat Oct 25, 2008 4:15 pm

Re: could not calculate i (2)

Post by Xeno » Mon Feb 02, 2009 3:59 pm

Fixed. A late beta had usurped the position of the real 12E in iTunes so of course there was no longer an update comparison. I "bought" 12E again and now have the latest, properly dysfunctional version :lol:.

theDev
Posts: 240
Joined: Mon Aug 04, 2008 8:58 pm

Re: could not calculate i (2)

Post by theDev » Fri Feb 06, 2009 9:35 am

Roy and I have installed the fix, and it was uploaded to Apple this morning. Expect an update shortly!

For those that are curious, the problem arose because I was programming a solution with more precision than is 100% reliable using IEEE floating point math, so in the effort to eek the 15th decimal place from the interest rate in some situations the calculation would not "settle down" at that last decimal place. Since any failure to settle down makes it appear as if the solution isn't behaving I was declaring an inability to solve for the interest rate. Being a little less picky about what constitutes "settled down" in the last decimal place has addressed the problem.

Kim

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