Re: solve ODE help?

*To*: mathgroup at smc.vnet.net*Subject*: [mg72238] Re: solve ODE help?*From*: "dimitris" <dimmechan at yahoo.com>*Date*: Fri, 15 Dec 2006 07:06:52 -0500 (EST)*References*: <eljb9d$7h0$1@smc.vnet.net><eloqtg$o1v$1@smc.vnet.net>

Among the list of references that Jean-Marc offered you see also the following technical notes from wolfram's site http://library.wolfram.com/infocenter/TechNotes/18/ http://library.wolfram.com/infocenter/TechNotes/21/ Regards Dimitris Ï/Ç Jean-Marc Gulliet Ýãñáøå: > learner wrote: > > Hi, everyone, > > i am new to solve ode in mathematica. i am trying to solve two > > odes(not for hw :)). > > y'+ytan(x)=sin(2x) > > > > I use: NSolve[{Direvative[1][y][x]+y Tan[x]==Sin[2x]},y,x] > > > > and get reply saying that: > > InverseFunction::ifun: Inverse functions are being used. Values may be > > lost for multivalued inverses > > > > {{y[x]->cot[x](sin[2x]-y'[x]}} , > > the mathematica did not solve the equation?? > > > > Furthermore, I add condition that y==2 when x==0 by saying: > > > > NSolve[{Direvative[1][y][x]+y Tan[x]==Sin[2x],y[0]==2},y,x] > > > > but no help ? why? > > thanks > > > > For differential equations, the functions that must be used are DSolve > [1] or NDSolve [2]. (Especially, read the sections called "Further > Examples"). A general presentation can be found in The Mathematica Book. > (For instance see [3].) Detail explanations of all the intricacies can > be found in [4]. > > In[1]:= > DSolve[{Derivative[1][y][x] + y[x]*Tan[x] == Sin[2*x]}, y, x] > > Out[1]= > {{y -> Function[{x}, C[1]*Cos[x] - 2*Cos[x]^2]}} > > In[2]:= > DSolve[{Derivative[1][y][x] + y[x]*Tan[x] == Sin[2*x], y[0] == 2}, y, > x] > > Out[2]= > {{y -> Function[{x}, -2*(-2*Cos[x] + Cos[x]^2)]}} > > Regards, > Jean-Marc > > 1. http://documents.wolfram.com/mathematica/functions/DSolve > > 2. http://documents.wolfram.com/mathematica/functions/NDSolve > > 3. http://documents.wolfram.com/mathematica/book/section-1.5.9 > > 4. > http://documents.wolfram.com/mathematica/Built-inFunctions/AdvancedDocumentation/DifferentialEquations/