Hello,
here is for the background : http://en.wikipedia.org/wiki/Lane-Emden_equation
and indeed checking for n=1 that sin(x)/x is a solution :
In [16]: diff(sin(x)/x, x,2)+2/x*diff(sin(x)/x,x)+sin(x)/x
works like a charm.
But:
In [14]: dsolve(f(x).diff(x, x)+2/x*f(x).diff(x)+f(x),f(x))
Out[14]:
C
Hi Johann
On Thu, Mar 5, 2009 at 6:28 AM, johannct wrote:
>
> Hello,
> here is for the background : http://en.wikipedia.org/wiki/Lane-Emden_equation
> and indeed checking for n=1 that sin(x)/x is a solution :
> In [16]: diff(sin(x)/x, x,2)+2/x*diff(sin(x)/x,x)+sin(x)/x
> works like a charm.
Exc
ok I looked at the code in solvers.py, l.606:
r = eq.match(a*f(x).diff(x,x) + b*diff(f(x),x) + c*f(x))
if r:
r1 = solve(r[a]*x**2 + r[b]*x + r[c], x)
if r1[0].is_real:
if len(r1) == 1:
return (Symbol("C1") + Symbol("C2")*x)*exp(r1[0]*x)
On Thu, Mar 5, 2009 at 9:55 AM, johannct wrote:
>
> ok I looked at the code in solvers.py, l.606:
> r = eq.match(a*f(x).diff(x,x) + b*diff(f(x),x) + c*f(x))
> if r:
> r1 = solve(r[a]*x**2 + r[b]*x + r[c], x)
> if r1[0].is_real:
> if len(r1) == 1:
> re
