PDE Toolbox help required in specifying nonzero m and d coefficients.

Hello,

I want to solve the following pde,

\partial_{tt} u + a\partial_t u = \partial_{xx} u - sin (u) + j(t)

But I am stuck at specifying d coefficient in pde toolbox. It says d must be a matrix when m is nonzero. My required value for d is 1. How can I specify it as a matrix?

[Joanna Chang]

I am also stuck on the same problem. I have two PDEs, and d should be 0 for the first one and 0.3 for the second such that d=[0 0; 0 0.3]. Following instructions here, I got that results.M is size 318x318. How can I express d as a matrix of this size?