At the initial time t = t0, for all x the solution components satisfy initial conditions of the form
(10-6)
At the boundary x = a or x = b, for all t the solution components satisfy a boundary condition of the form
(10-7)
q(x,t) is a diagonal matrix with elements that are either identically zero or never zero. Note that the boundary conditions are expressed in terms of the f rather than partial derivative of u with respect to x ∂u/∂x. Also, of the two coefficients, only p can depend on u.