Re: System for which Solve and NSolve both fail
- To: mathgroup at smc.vnet.net
- Subject: [mg30589] Re: [mg30572] System for which Solve and NSolve both fail
- From: BobHanlon at aol.com
- Date: Thu, 30 Aug 2001 03:51:35 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 2001/8/29 8:46:22 AM, writes: >Needs["Graphics`ImplicitPlot`"]; > >Needs["Graphics`Colors`"]; > >Solve and NSolve are primarily for polynomial equations. Use FindRoot > >eqns = {3^x + 3^y == 90, x + y == 6}; > >ImplicitPlot[eqns, {x, 1, 5}, {y, 1, 5}, PlotStyle -> {Red, Blue}]; > >FindRoot[eqns, {x, 4.1}, {y, 2.2}] // Rationalize[#, 1*^-8]& > >{x -> 4, y -> 2} > >FindRoot[eqns, {x, 2.2}, {y, 4.1}] // Rationalize[#, 1*^-8]& > >{x -> 2, y -> 4} > >eqns /. {%, %%} > >{{True, True}, {True, True}} > You can "force" Solve as follows Transpose[{xSoln = Solve[3^x + 3^y == 90 /. (ySoln = Flatten[ Solve[x+y == 6, y]]), x], ySoln /. xSoln}] Bob Hanlon Chantilly, VA USA