[R] how to plot a differential equation?

Moshe Olshansky m_olshansky at yahoo.com
Thu Aug 2 06:52:50 CEST 2007

Hi Montserrat,

What exactly would you like to plot?

Your differential equation can be easily integrated so
that you can get an implicit expression for F(x), i.e.
expression like G(c,x,F(x)) = 0 where G is a known
function and c is an arbitrary constant. For every
value of c and each value of x such that x < (-1/k2 +
(k1+k2)*ln(k1+k2)/k2^2) [if my calculations are
correct!] there exist 2 possible values of F(x): one
with F(x) <1 and one with F(x) > 1. So for each c you
have two branches of the function F defined for x <
x(c). You will need a numerical procedure to find
these two values of F(x).



--- Montse Rue <montse.rue at gmail.com> wrote:

> Hi,
> I would like to plot the following equation:
> dF(x)/dx=(k1+k2F(x))(1-F(x))
> where k1 and k2 are parameters that I have estimated
> already.
> How can I plot the curve in R?
> Thanks!
> Montserrat Rue
> Universitat de Lleida (Spain)
> 	[[alternative HTML version deleted]]
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