**Dear all,**

**I have one quetion. I have written maple code based on Dr.Robert J. Lopez's one.**

**Here is my code.**

**> q1 := diff(x(t),t) = -a*x(t)*y(t) + b*z(t);**

**q2 := diff(y(t),t) = -a*x(t)*y(t) + b*z(t);**

**q3 := diff(z(t),t) = a*x(t)*y(t) - b*z(t);**

**q4:=k(t)=x(t)*y(t)/z(t);**

**ic := x(0)=10,y(0)=10,z(0)=0;**

C := < I put Experimental data….>:

**> SS := proc(a,b)**

**local F, V;**

**if not type([a,b],['numeric','numeric']) then return 'SS'(a,b);**

**elif a<0 or b<0 then return 1e100;**

**end if;**

**F := dsolve(eval({q1,q2,q3,q4,ic},{:-a=a,:-b=b}),[x(t),y(t),z(t),k(t)],numeric, output=Array([seq(k,k=0..N)]));**

**V := convert(Column(F[2,1],5),Vector);**

**Norm(V-C,2);**

**end proc:**

I just put one more equation -eqn4. it is not differential equation.

I currently have error massage from maple. Could you let me know how I solve the equations in this case?

Thanks.