Re: seruous solve bug? only when used with simplifying

*To*: mathgroup at smc.vnet.net*Subject*: [mg48693] Re: [mg48634] seruous solve bug? only when used with simplifying*From*: sean kim <sean_incali at yahoo.com>*Date*: Thu, 10 Jun 2004 02:44:35 -0400 (EDT)*Reply-to*: sean_incali01 at yahoo.com*Sender*: owner-wri-mathgroup at wolfram.com

ok. now I see where I made a mistake from your comments and other's... I Didn't mean to insinuate that a function you made had bugs. It just seemed at the time to be incorrect. Solve came before simplify and fullsimplify. I didn';t include it because it was kinda long routine. sorry everyone. sean (i'm too scared to ask about Solve[] function now. kidding. lol) --- Daniel Lichtblau <danl at wolfram.com> wrote: > sean kim wrote: > > hello group, > > > > i think i have a serious Solve[], Simplify[], > FullSimplify[] bug... > > > > > > Take a system of equations as below. (apb is > actually (a+b). i defined > > it as apb to keep Mathematica crunching away at > it) > > > > sys = > > {c1[t] == (c*(16*a^4 + 8*a^3*kd + 4*a^2*apb*kd + > 2*a*apb^2*kd + > > apb^3*kd))/(apb^4*kd), > > c2[t] == (2*(8*a^3 + 4*a^2*apb + 2*a*apb^2 + > apb^3)*b*c)/(apb^4*d), > > c3[t] == (2*(8*a^3 + 4*a^2*apb + 2*a*apb^2 + > apb^3)*b*c)/(apb^4*kd)} > > > > sys1 = sys /.{apb -> (a + b)} > > sys2 = sys/.{apb -> (a + b)}//Simplify > > sys3 = sys/.{apb -> (a + b)}//FullSimplify > > > > and then use > > > > TrueQ[sys1 == sys1] > > TrueQ[sys1 == sys2] > > TrueQ[sys1 == sys3] > > TrueQ[sys2 == sys3] > > > > then it gives, > > > > Out[18]=True > > Out[19]=False > > Out[20]=False > > Out[21]=False > > > > Simplify and FullSimplify changed the system so > much that they are not > > equal? > > > > Basically, unless I define the (a+b) as a single > constant apb, the Mathematica > > will do soemthing with it then it messes it up. I > think... > > > > Why is this happening? and how do i prevent it > from happening again > > with other more obsucre systems? Above I got > lucky in finding the > > cause (a+b) > > > > thanks in advance for any and all comments. > > > > Sean > Umm, where did you use Solve? What would make you > think you have > anything other than a serious lack of understanding > of the semantics of > Mathematica's Equal? Why did you not check section > 1.5.5 of The > Mathematica Book, accessible through a link from > Equal in the Help > Browser? Why would you formulate an utterly > misleading subject header > for a note such as this? > > > Daniel Lichtblau > Wolfram Research > > __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/