Bug in converting complex numbers?
07-03-2018, 08:01 AM
Post: #1
 blevita Junior Member Posts: 29 Joined: Jun 2018
Bug in converting complex numbers?
Hi

I have tried to convert a complex number in the style of 100*exp(60 Deg)
Usually they should be converted to something like:

100*(cos(60)+i*sin(60)) = 50+86.6*i

But the Prime converts the expression 100*exp(60 Deg) to -95.24 - 30.48*i
This is a strange behaviour to me.

Do i have to enter the complex number in an other way?
Or is this a software bug?

Attached a picture

Thank

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07-03-2018, 08:17 AM (This post was last modified: 07-03-2018 08:19 AM by blevita.)
Post: #2
 blevita Junior Member Posts: 29 Joined: Jun 2018
RE: Bug in converting complex numbers?
I have tested this behaviour a little bit more.
It looks like there is a serious bug in the Prime.

If i extract the RE part within the CAS it gives me the correct value of 50.
If i extract the exact same thing withing the Calculator it gives me -95.

If i approx the value within the CAS, also the CAS fails to convert correctly!

Take a look at the pictures.

Attached File(s) Thumbnail(s)

07-03-2018, 08:59 AM (This post was last modified: 07-03-2018 09:03 AM by sasa.)
Post: #3
 sasa Member Posts: 116 Joined: Apr 2018
RE: Bug in converting complex numbers?
I do not have a Prime, however, this sems to be a problem misrepresenting input is in degree or radian and further result representation.

Do you have to set independently degree and radian for each calculator mode (HOME/CAS)?

If you check manually, you will see that second result is correct if numbers are expected in radian: sin(60)=-0,3048106211 and so on.
07-03-2018, 09:03 AM (This post was last modified: 07-03-2018 09:07 AM by blevita.)
Post: #4
 blevita Junior Member Posts: 29 Joined: Jun 2018
RE: Bug in converting complex numbers?
(07-03-2018 08:59 AM)sasa Wrote:  Do you have to set independently degree and radian for both calculator modes (HOME/CAS)?

If you check manually, you will see that second result is correct if numbers are expected in radian: sin(rad(60))=-0,3048106211 and so on.

Ok interessting.
I have set the CAS and calculator to Degrees.
You can see this also on the top right corner where you see the green Dregree symbol.
I have also swithed to radians without success.

But you are right. If i enter radians, the answer is correct.
07-03-2018, 09:11 AM (This post was last modified: 07-03-2018 09:13 AM by sasa.)
Post: #5
 sasa Member Posts: 116 Joined: Apr 2018
RE: Bug in converting complex numbers?
Notice that x in exp(x) is not expected to be an angle, thus you have to do conversion manually.
07-04-2018, 11:04 AM
Post: #6
 Nigel (UK) Senior Member Posts: 463 Joined: Dec 2013
RE: Bug in converting complex numbers?
In general, trig functions on the Prime interpret any complex number as being in radians. For example, in degrees mode sin(30) is 0.5, but sin (30+0*i) is -0.988, even when a degrees sign is added after the "30".

I believe this is standard practice on calculators that support trig and exponential functions with complex arguments, so it should be viewed as a feature, not a bug!

Nigel (UK)
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