RE: positive root only using Solve[]
- To: mathgroup at smc.vnet.net
- Subject: [mg41821] RE: [mg41791] positive root only using Solve[]
- From: "John C. Erb, Ph.D." <John_C_Erb at prodigy.net>
- Date: Fri, 6 Jun 2003 09:50:52 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello, Will Select[x /. Solve[x^2 - 1 == 0, x], # > 0&] do what you want? For more general equations you might need to specify that x is to be Real as well as positive. Select[x/.Solve[x^2-1\[Equal]0,x],(#\[Element]Reals&&#>0)&] John C. Erb email: John_C_Erb at prodigy.net -----Original Message----- From: seferiad [mailto:seferiad at pacbell.net] To: mathgroup at smc.vnet.net Subject: [mg41821] [mg41791] positive root only using Solve[] Hello, Consider the following equation. Solve[x^2 ==1, x] Mathematica will output 1 and -1 for x. However, I only want Mathematica to output the positive solution (i.e., x -> 1), so I can use this conveniently in a subsequent equation. Is there a way to force the output to produce only the positive solution? Thanks, Jay