Re: Solve[] handles the same system differently
- To: mathgroup at smc.vnet.net
- Subject: [mg40858] Re: Solve[] handles the same system differently
- From: "Bill Bertram" <wkb at ansto.gov.au>
- Date: Tue, 22 Apr 2003 06:46:35 -0400 (EDT)
- Organization: Australian Nuclear Science and Technology Organisation
- References: <b80k0i$m3f$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"Joe Gwinn" <joegwinn at attbi.com> wrote in message news:b80k0i$m3f$1 at smc.vnet.net... > I am running Mathematica 4.0.1.0 under MacOS 9.1, and have encountered a > little mystery: > > > The following works OK: > > In[15]:= > Solve[{Rx == 3300, VinX1 == 0, > IdsX1 == 0.001(1 - (VinX1 - Rx*IdsX1)/(-1.5))^2}, {IdsX1}] > > Yielding: > > Out[15]= > {{IdsX1 -> 0.000234453}, {IdsX1 -> 0.00088125}} > > > When I rearrange the equation system a bit, it fails to find a solution: > > In[16]:= > Solve[{Rx == 3300, VinX1 == 0, VgsX1 == Rx*IdsX1, > IdsX1 == 0.001(1 - (VinX1 - VgsX1)/(-1.5))^2}, {IdsX1}] > > Out[16]= > {} Hi Joe, Your second system is now contains two unknowns, the easiest way to fix it is by changinge the final bracket {IdsX1} to {IdsX1,VgsX1}. Cheers, Bill