Question about Solve (on mma2.2)

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Question about Solve (on mma2.2)*From*: haras at vermeer.c.u-tokyo.ac.jp*Date*: Sat, 18 Dec 93 21:51:06 +0900

Hello, Please tell me how to get roots(intersection?) of simultaneous nonlinear equations when variables are REAL. Example1: [ x,y,z are real variables.] --- f1 = x^2 + y^2 + z^2 -1; f2 = (x-2)^2 + y^2 + z^2 -1; Solve[ f1==0 && f2==0, {x,y,z}] Out[3]= {{y -> -I z, x -> 1}, {y -> I z, x -> 1}} --- {x->1,y->0,z->0} is a result that I want. Example2: [ x,y,z are real variables.] --- f1 = x^2 + y^2 + z^2 -1; f2 = (x-5)^2 + y^2 + z^2 -1; Solve[ f1==0 && f2==0, {x,y,z}] 2 2 Out[3]= {{y -> -Sqrt[-3 - z ], x -> 2}, {y -> Sqrt[-3 - z ], x -> 2}} --- In this case , {f1==0} does not intersect {f2==0} and Sqrt[-3-z^2] is not real when z is real. My ideal result is a null list. Is it necessary to use a Package for nonlinear programming ? Thanks in advance. HARASHIMA Seigo ( haras at vermeer.c.u-tokyo.ac.jp )