Re: [Boost-users] odeint feedback request

Subject: Re: [Boost-users] odeint feedback request
From: Larry Evans (cppljevans_at_[hidden])
Date: 2011-10-25 07:20:06

On 10/23/11 15:40, Karsten Ahnert wrote:
> Dear community,
> 
> odeint is a library for solving ordinary differential equations 
[snip]
> The library and the documentation are
> available at the github:
> 
> https://github.com/headmyshoulder/odeint-v2
> http://headmyshoulder.github.com/odeint-v2/doc/index.html
[snip]
The page:

http://headmyshoulder.github.com/odeint-v2/doc/boost_sandbox_numeric_odeint/getting_started/short_example.html

says:

  The equations of motion are given by x'' = -x + γ x'. This can be
  transformed to a system of two coupled first-order differential
  equations with new variables x and p=x'. To apply numerical
  integration one first has to design the right hand side of the
  equation w' = f(w) where in this case w = (x,p):

which initially confused me because x was not a new variable as
claimed by:

  new variables x and p=x'

I think it would be clearer if it read:

  with new variables w_1=x and w_2=x'.

and then:

  w = (w_1,w_2)

which would emphasize that w was a vector and f was a function taking
a vector and returning a vector.

-regards,
Larry