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# HP 39gII BUG: complex numbers and powers

06-07-2014 04:24 PM

Thr following:

(0.02+0.01*i)^3 results in:

1.14486680448E−11+6.29676742464E−11*i

the correct answer is:

.000002+.000011*i

the correct answer can be obtained by entering (0.02+0.01*i)*(0.02+0.01*i)*(0.02+0.01*i).

Firmware version: 30/Oct/2013 Rev: 19148

I found this while using the calculator at work. I had put it aside due to previous frustrations, but this past week I decided to use it again - *and very soon I run into a problem*.

This calculator has been for sale for almost two years. The last update was more than 6 months ago. It still has serious bugs. Is this becoming the forgotten brother of the Prime?

Whenever I complain about the 39gii, I get reminded that other HP calulators e.g. 48GX also had bugs, *but these have never affected me in daily work!*

Unfortunately I *am* losing my faith in the current development team.

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## HP 39gII BUG: complex numbers and powers

06-09-2014 07:16 AM

Even weirder :

(0.02+0.01i)^1 = 0.0003577708764+0.0001788854382i

the ^ must be doing something other than raising to a power....

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## HP 39gII BUG: complex numbers and powers

06-09-2014 09:44 AM

Further to this:

Using the x² function gives correct answer, using ^2 "to power of 2" gives erroneous answer.

Also when using larger numbers correct answers result, e.g.:

(2.15+1.25*i)^3 results in correct answer of −.13975+15.38125*i

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## HP 39gII BUG: complex numbers and powers

06-09-2014 03:43 PM

It looks to me to be the case that as long as one of |a| or |b| is greater than 1 (not equal) in a+bi you'll get the correct answer when raising it to a power.The closer to zero the maximum of a and b is, the bigger the error!.

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## HP 39gII BUG: complex numbers and powers

06-10-2014 02:45 AM

Mmmm-- wrote:It looks to me to be the case that as long as one of |a| or |b| is greater than 1 (not equal) in a+bi you'll get the correct answer when raising it to a power.The closer to zero the maximum of a and b is, the bigger the error!.

Unfortunately the numbers I use are not limited to the "good" range.

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## HP 39gII BUG: complex numbers and powers

06-10-2014 03:16 PM

(2+i)^3/100^3 works, (just to get the a>1).

But really that is just ridiculous!

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## HP 39gII BUG: complex numbers and powers

07-30-2015 09:27 AM

So, more than a year after posting this and still no update in sight!

Apparently it is a faulty implementation of LN for complex arguments.

http://www.hpmuseum.org/forum/thread-3750-post-34071.html#pid34249

Indeed try:

LN(0.01+0.01i)

HP-39gii answer: -9.210340+0.785398i

Correct answer: -4.258597+0.785398i

Bah humbug.

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## HP 39gII BUG: complex numbers and powers

07-31-2015 10:08 AM

Hi!, Mnnn:

See this document, with version 19157, for Connectivity Kit, in HP39GII ... https://tiplanet.org/forum/viewtopic.php?t=13482&p=153154#p153154

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## HP 39gII BUG: complex numbers and powers

07-31-2015 11:10 AM

Thank you for the link, however that is the exact same version that I have and that __has the bug__.

@Maké wrote:Hi!, Mnnn:

See this document, with version 19157, for Connectivity Kit, in HP39GII ... https://tiplanet.org/forum/viewtopic.php?t=13482&p=153154#p153154

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## HP 39gII BUG: complex numbers and powers

08-01-2015 04:25 PM

For what it's worth, the Prime gives correct answers to your examples. 😕