Hi Friends My name is Sayed Hoseini and I am PhD student in University of Wollongong. Could you please have a look on this problem and let me know about any package/s which might be used for solving that? I came across to this problem in my research: We have a linear system including two differential equations and two variables; For example consider the following system: L*U=H Where: [diff(,x$2)+I*w q ] L=[ ] [q diff(,x$2)- I*w] and [u(x)] U=[ ] [v(x)] that u and v are functions of x and w, q and H are functions of x too, but fixed and I is the complex argument .