Derivative of Interpolation Functions

Dear all,

I am trying to understand if, given an interpolation function (defined by a table of points in an external file like *.txt file) it is possible to define the derivative (spatial) of the interpolation function to insert in the weak formulation.

Let's suppose I have a convection term in my equation where the velocity of the convection is given by an interpolation function. When I compute the weak formulation, I'll have the spatial derivative of that function. Does Comsol recognize them if, when I define the weak formulation I have dx(interpolatedFunction) ?

Many thanks,

Paolo