InputParameters validParams<CoefDiffusion>() { InputParameters params = validParams<Kernel>(); params.addParam("coef", 0.0, "Diffusion coefficient"); params.addParam<FunctionName>("function", "If provided, the diffusion coefficient will be coef + this function. This is useful for temporally or spatially varying diffusivities"); params.addClassDescription("Kernel for diffusion with diffusivity = coef + function"); return params; }