Possible bug in CAS?

01252016, 08:14 PM
(This post was last modified: 01252016 08:24 PM by MrMcChicken.)
Post: #1




Possible bug in CAS?
Hello,
I am doing some really basic calculations with complex numbers. After entering some random stuff I think I found a bug. If I enter: simplify(squareroot(x^2*y^2)) my Prime shows: x*y. The emulator shows: abs(x)*abs (y) which is fine. Both run on the latest Firmware (8151). Can somebody confirm this issue? Greetings, MrMcChicken Edit: It happens too with simplify(squareroot((x^4*y^4)) = x^2*y^2 

01252016, 09:24 PM
Post: #2




RE: Possible bug in CAS?
(01252016 08:14 PM)MrMcChicken Wrote: If I enter: simplify(squareroot(x^2*y^2)) my Prime shows: x*y.mine gives expected result : abs(x)*abs(y) primer 

01252016, 09:58 PM
Post: #3




RE: Possible bug in CAS?
(01252016 09:24 PM)primer Wrote: mine gives expected result : abs(x)*abs(y)mine also. Please, check the CAS Settings: I've Exact, Use β, Principal, not: Complex, use i, increasing. Simplify minimum... Salvo β«aLβ0mic (IT9CLU) :: HP Prime 50g 41CX 71b 42s 39s 35s 12C 15C  DM42, DM41X  WP34s Prime Soft. Lib 

01252016, 11:46 PM
(This post was last modified: 01252016 11:48 PM by primer.)
Post: #4




RE: Possible bug in CAS?
(01252016 09:58 PM)salvomic Wrote: I've Exact, Use β, Principal, not: Complex, use i, increasing. Simplify minimum...same as you : three options on left are checked (exact...) and three ones on the right are not. Maybe you defined an "assume" ? or something like that ? I never remember where we can see existing assumes, but I think purge() cmd does remove all of them, check help before usage, just in case... Regards. primer 

01262016, 09:13 AM
Post: #5




RE: Possible bug in CAS?
I found the source of the problem. If "use i" is checked i get x*y as a result.
Why is this so? Is this a bug? Thanks for help so far. Greetings, MrMcChicken 

01262016, 11:41 AM
Post: #6




RE: Possible bug in CAS?
If you set complex mode on ("use i" on the Prime), then sqrt(x^2) is no more equal to x and the system chooses one of the two complex square roots.
Should perhaps be somewhere in a FAQ. 

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