HP Prime Bug? (875 Views)
Frequent Advisor
Posts: 53
Registered: ‎09-29-2012
Message 1 of 5 (875 Views)

HP Prime Bug?

I entered the following in CAS screen:


Collect(( 8*x^3*y^2)^1/2) , meaning square root of 8x^3y^2  (see attachment)


I got: -2* square root of x * square root of 2 * y *x


Why the negative?



Trusted Contributor
Posts: 110
Registered: ‎09-25-2006
Message 2 of 5 (829 Views)

Re: HP Prime Bug?

Must be a bug.  Simplified version:

collect(sqrt(2*x^2)) --> -sqrt(2)*x

Should be sqrt(2)*|x|, of course.

Occasional Advisor
Posts: 9
Registered: ‎12-23-2011
Message 3 of 5 (770 Views)

Re: HP Prime Bug?


You can get the correct answer without using collect:

Just enter your expression and tap the simplify button on the screen.

Another workaround is.... collect(sqrt(abs(8*x^3*y^2))) enter

Note: make sure that complex in the cas setup in unchecked.


As Joseph noted, there is something odd in how the cas works.


Frequent Advisor
Posts: 53
Registered: ‎09-29-2012
Message 4 of 5 (620 Views)

Re: HP Prime Bug?

[ Edited ]

Hi Joseph!


Thanks for the response.

I know there are other ways. The point is, that when you find a bug like this , the trust in the equipment suffers. Even more, if two months after reported, NO one from HP have said anything about it. BTW, if I use the "factor" function, instead of "collet", you'll get same error.


This time it was easy to spot the error because it is a simple expression. What if it was a complicated expression which you can't double check by hand? Who knows how widespread the error is...

To me it is a big issue, not to be taken lightly!

Honored Contributor
Posts: 817
Registered: ‎01-08-2009
Message 5 of 5 (606 Views)

Re: HP Prime Bug?

[ Edited ]

It has not been taken lightly. No issue reported is ever taken lightly. The issue is that HP policy forbids employees from making any sort of future statements unless you are officially empowered by the company to do so.


What I am allowed to say is, "Thank you for your report on this potential issue. It will be placed on a list of items for investigation."





Forgot to mention, I missed your original note about this and didn't see it until about 3-4 weeks or so past. I didn't want to post on something already so that is why I didn't ackowledge it...




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