Re: solving for variable and then get these e's..?

*To*: mathgroup at smc.vnet.net*Subject*: [mg46931] Re: solving for variable and then get these e's..?*From*: Gregor Pfyffer <g.pfyffer at oma.be>*Date*: Tue, 16 Mar 2004 19:54:56 -0500 (EST)*References*: <c33de2$ftc$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

I found your error! You don't assign a random value to the variable e you define in In[270], but therfore you twice dfine a value to d ! I assume this to be a copy-paste error. ;-)) Kind regards Gregor sean kim wrote: > Hello Group. > > I was playing around with lorenz system again. I assigned random > numbers for all the parameters. and made a steady state system based > on that and solved for the variables. and I get the following. ( the > code is at the bottom) > > {y[0] == 0.1889025652295933*(-1.3382047869208344 - > 0.47590327034877034*Sqrt[7.906927918602607 - > 18.515309886236974*e]), > x[0] == 0.31792235868739005*(1.5727110293983604 + > 0.5593002876087739*Sqrt[7.906927918602607 - > 18.515309886236974*e]), > z[0] == 0.042970475451898735*(7.906927918602607 + > 2.8119260158479644*Sqrt[7.906927918602607 - > 18.515309886236974*e]} > > What are those little e's at the end of the solutions? Is that euler's > number? and why can't I use that in NDSolve routine? are those > signifcant? > > any thoughts are appreciated. > > In[270]:= > ode = {x'[t]== -a y[t]-b z[t],y'[t]== c x[t]+d y[t], > z'[t] == e-f z[t]+f x[t] z[t]} > > %/._'[t]->0 > > Solve[%,{x[t], y[t], z[t]}] > > %/.{a-> Random[Real, {1, 3}], b-> Random[Real, {1, 3}], > c-> Random[Real, {1, 3}],d-> Random[Real, {1, 3}], > d-> Random[Real, {1, 3}],f-> Random[Real, {1, 3}]}/.Rule ->Equal/.t-> > 0 //InputForm > > s1 =% [[1]] > s2 = %%[[2]] > > NDSolve[Join[{x'[t]\[Equal]-a y[t]-b z[t],y'[t]\[Equal]c x[t]+d y[t], > z'[t]\[Equal]e-f z[t]+f x[t] z[t]}, s1], {x[t], y[t], z[t]}, {t, > 0, 10}] >