MathGroup Archive 2013

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: A question about numerically solving differential equations


In your second DE below, you should type NDSolve, not NDSOlve. Also, 
your "primes" that indicate derivatives are "back quotes" use the 
regular single quote (apostrophe):

NDSolve[{y'[x] == g[x], g'[x] == g[x] + y[x], g[1] == 1,
   y[1] == 1}, {y, g}, {x, 1, 2}]

As for the first one, I can't say, since you did not post any initial 
conditions.

Cheers,

Kevin

On 4/2/2013 3:25 AM, debguy wrote:
> 2 D[f0[r], r]/r + D[f0[r], r, r] == -2 A f1[r]/r^4 +  2 A D[f1[r], r]/
> r^3
> -2 f1[r]/r^2 + 2 D[f1[r], r]/r + D[f1[r], r, r] == 2 A D[f0[r], r]/
> r^3
>
> I tried it later.  I cannot get anything
>            y`[x]==g`[x]==y[x]==g[x]
> to work using any conditions i try.
>
> NDSOlve[{ y`[x]==g[x], g`[x]==g[x]+y[x], g[1]=1, y[1]=1 },{y,g},{x,
> 1,2} ]  (* foo *)
>
> Is the only form I can get to work using two funs.  Which is what the
> book example uses.
>
> I'm unsure how to re-express your eq'n that way to try it.
>



  • Prev by Date: 3D ViewPoint Selector (V5.2) in higher Mathematica versions ?
  • Next by Date: plotting qC and better way for IIC
  • Previous by thread: Re: A question about numerically solving differential equations
  • Next by thread: Re: A question about numerically solving differential equations