Using jacobs for multivariable equations?

[tessaract87]

Hi all,

I'm trying to use the jacobian function jacobs from the optim package to do
a stability analysis on a system of ODEs.  The equations of interest are:

u(1-u/0.2)-u*v

and

1*(u-1)*v

But when I tried to enter them into Octave and run them through jacobs, this
happens:

 f = @(u,v) [u(1-u/0.2)-u*v;1*(u-1)*v];
>> pkg load optim
>> Df1=jacobs([0,0],f(u,v))
error: 'u' undefined near line 1 column 19
error: evaluating argument list element number 1
error: evaluating argument list element number 2

I'm guessing this either because a)I screwed up the formatting of the
equation when putting it into octave, or b)jacobs can't handle multivariable
equations (every example I've seen was a single variable equation).  Is
there a way to get jacobs to handle equations like this?  Alternatively, is
there another method of getting the jacobian?

Thanks!



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