Possible bug in CAS? - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Possible bug in CAS? (/thread-5591.html) Possible bug in CAS? - MrMcChicken - 01-25-2016 08:14 PM 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 RE: Possible bug in CAS? - primer - 01-25-2016 09:24 PM (01-25-2016 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) RE: Possible bug in CAS? - salvomic - 01-25-2016 09:58 PM (01-25-2016 09:24 PM)primer Wrote:  mine gives expected result : abs(x)*abs(y) mine also. Please, check the CAS Settings: I've Exact, Use √, Principal, not: Complex, use i, increasing. Simplify minimum... Salvo RE: Possible bug in CAS? - primer - 01-25-2016 11:46 PM (01-25-2016 09:58 PM)salvomic Wrote:  I've Exact, Use √, 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. RE: Possible bug in CAS? - MrMcChicken - 01-26-2016 09:13 AM 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 RE: Possible bug in CAS? - parisse - 01-26-2016 11:41 AM 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.