Re: differential equation solve

*To*: mathgroup at smc.vnet.net*Subject*: [mg68841] Re: differential equation solve*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Mon, 21 Aug 2006 03:27:37 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <ec97f9$4bn$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

elvis wrote: > another equation: > > \!\(DSolve[{\(x'\)[t] == r*x[t] \((1 - x[t]\/xm)\), x[0] == x0}, x, > t]\) > > this face anothe prolbem Assuming that the "problem" you faced is the *warning* message returned by DSolve, you can easily check that the returned solution is correct: sol = DSolve[{Derivative[1][x][t] == r*x[t]*(1 - x[t]/xm), x[0] == x0}, x, t] --> Solve::"ifun" : "Inverse functions are being used by (Solve), so some solutions may not be found; use Reduce for complete solution information. --> {{x -> Function[{t}, E^(r*t)*x0*(xm/(-x0 + E^(r*t)*x0 + xm))]}} Simplify[{Derivative[1][x][t] == r*x[t]*(1 - x[t]/xm), x[0] == x0} /. sol[[1]]] --> {True, True} HTH, Jean-Marc