hello

i've got one problem in modelling capacitor

i wrote

I(vp,vn) <+ ddt(c*V(vp,vn))

but c=25*limexp(-23.3*V(vin_p,vin_n))

the error message is

           line 16: Error: An operand dependent on the output of a dot() operator
       (dynamic expression) can not be used in a multiplication operation when
       the other operand is dependent on a probe or the simulation time.
       Consider using a node to hold the dynamic expression and probe this
       node in the multiplication operation.
       See also the section of the SpectreHDL reference manual describing
       "Time Derivative Operator".

i am beginer and don't understand the proposed solution starting with consider

can you explain me how to fix it?

regards

right, thank you