title: time derivative of a variable as a signal and not as a function
body: <p>In Modelica, I have a variable x which is dependent on (a, b,c). For a given simulation time, its plot (x,time) looks smooth and continuous. I would like to have the slope of this curve without having to explicitly differentiate der(x) because I get errors regarding the partial derivatives with respect to a, b or c. Is this possible? In other words I want the slope of the final output, without having to differentiate what it is behind it.</p>