time dependent diffusion coefficient

Hi,

I'm trying to solve the diffusion equation with time dependent c and f coefficients. The diffusion coefficient c is a function of temperature T and the temperature varies with time (t) :

% diffusion coefficient (c_coeff)
T = a*exp(-b*t) - d*t + h
c = D*exp(E/(R*T))

% source term
s = m*exp(n*t)

Can you help me to express these coefficients as functions that can be used in Pdetool or in the following code?

model = createpde();

% Call the geometry considered to solve the PDE
[ dl ] = geometry () ;
geometryFromEdges(model,dl);

%Apply Dirichlet Boundary conditions
applyBoundaryCondition(model,'dirichlet','Edge',1:model.Geometry.NumEdges,'u',0);

% Define the time step
time = 0:0.01:1;

% Define pde coefficients
specifyCoefficients(model,'m',0,'d',1,'c',@c_coef,'a',0,'f',@source, 'face',1);

% Initial conditions
                      
setInitialConditions(model,0);

% Generate the Mesh
generateMesh(model,'GeometricOrder','linear');

% Solve the pde
results = solvepde(model,time);

Thanks