Question: set-of-ODEs-stiff

Dear guys

I have a set of ODEs but when I solve it maple shows this massage:

"Error, (in dsolve/numeric/SC/firststep) unable to evaluate the partial derivatives of f(x,y) for stiff solution"

If I neglect the option "stiff=true", it works but then when I want to plot something maple says:

"Warning, cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up"

and only shows a coordinate system, without any curve. Does anybody know what is the problem?

thanks.

Please Wait...