Dear All,

I have a problem with function that should smooth my output signal.
The transition(V(x), td,tr,tf) add to signal rise and fall times but only in linear way.
I have written following funkction based on Lagrange interpolation between three points (x1,y1) (x2,y2) , (x12,y12) and wanted signal, after smoothing to be more exponential, but I get convergence problem:
       "internal timestep too small in transient analysis"
Note that points(x,y) are changing in time.

analog function real fsmooth;
       input x,x1,y1,x12,y12,x2,y2;
       real x,x1,y1,x12,y12,x2,y2;
     real n1,n12,n2;
           begin
                 n1 = ((x-x12)*(x-x2))/((x1-x12)*(x1-x2));
                 n12 = ((x-x1)*(x-x2))/((x12-x1)*(x12-x2));
                 n2 = ((x-x1)*(x-x12))/((x2-x1)*(x2-x12));
                 fsmooth = n1*y1 + n12*y12 + n2*y2;
           end

     endfunction
Perhaps there is some embedded function to do this??

Thanks for your answers.
Best regards,
Dracon

The reason why it is not built into the language is because in practice, it is very rarely needed.  My experience is that people overuse smoothing, usually at great cost in modeling and simulation time. Can I ask why you think you need it?

-Ken