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Associate Professor
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HP 39gII BUG: complex numbers and powers

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.

 

-Bart
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Mmmm-- Tutor
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HP 39gII BUG: complex numbers and powers

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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Associate Professor
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HP 39gII BUG: complex numbers and powers

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

 

 

-Bart
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Mmmm-- Tutor
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HP 39gII BUG: complex numbers and powers

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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Associate Professor
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HP 39gII BUG: complex numbers and powers


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. :smileysad:

-Bart
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HP 39gII BUG: complex numbers and powers

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

 

But really that is just ridiculous!

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Associate Professor
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HP 39gII BUG: complex numbers and powers

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.

-Bart
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Distinguished Professor
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HP 39gII BUG: complex numbers and powers

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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Associate Professor
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HP 39gII BUG: complex numbers and powers

 

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


 

-Bart
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Teacher
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HP 39gII BUG: complex numbers and powers

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

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