Re: problems with DSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg99423] Re: [mg99375] problems with DSolve*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Tue, 5 May 2009 05:43:52 -0400 (EDT)*Reply-to*: hanlonr at cox.net

Read the documentation for Plot and look at the numerous examples that use Evaluate. Plot[Evaluate[x[t] /. DSolve[ {x'[t] == y[t], y'[t] == -x[t], x[0] == 1, y[0] == 2}, {x, y}, t]], {t, 0, 5}] Bob Hanlon ---- szymon.stoma at gmail.com wrote: ============= hello, i am new to mathematica, therefore sorry if my question is trivial. I would like to understand why the following line does not work: Plot[(x[t] /. DSolve[{x'[t] == y[t], y'[t] == -x[t], x[0] == 1, y[0] == 2}, {x, y}, t]), {t, 0, 5}] whereas after splitting into two lines it works: sol = DSolve[{x'[t] == y[t], y'[t] == -x[t], x[0] == 1, y[0] == 2}, {x, y}, t] Plot[(x[t] /. sol), {t, 0, 5}] i would like to use Manipulate to play with boundary conditions, so the first notation would be highly useful. thanks a lot for any feedback.