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Re: Help with differential equation

  • To: mathgroup at
  • Subject: [mg112257] Re: Help with differential equation
  • From: "Nasser M. Abbasi" <nma at>
  • Date: Tue, 7 Sep 2010 02:00:44 -0400 (EDT)
  • References: <i627tc$b9$>
  • Reply-to: nma at

On 9/6/2010 1:14 AM, mathpavi wrote:
> Dear experts,
> I tried solving  the following differential equation using DSolve:
> y' ' [x]+a( y' [x] ) = b( cos[y] )
> But I got error message which asked me to provide proper arguments for
> cos..
> So I changed cos[y] to cos[kx] and obtained solution...
> However, I have to solve the equation by keeping cos[y] in order to
> obtain a solution of relevance to my work.
> Please help.
> praveen

it is Cos not cos, (Mathemaica is case sensitive) and also you need to 
write y[x] not just y inside the Cos and need to use == not =


de = y''[x]+ a y'[x] == b Cos[ y[x] ]

DSolve[de, y[x], x]

But this is non-linear ode, may be try a numerical solution?


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