Dear Ken Kundert

I reallly appreciate your answer for my previous questions. Now I tried to directly use the behavioral model codes of divider without hidden state. Unfortunately, there is an error message.
###
Error found by spectre during SpectreHDL compile.
   …...
       line 40:  Error: (Archaic Syntax) Does not comply with the Accellera
       Verilog-AMS 2.0 Standard and beyond. To comply with the current
       standard, delete the null statement. Null statements (also known as
       empty statements and coded as just `;') can be used only in case or
       event control statements.
###
After then, I deleted the semicolon ( ; ) in the line 40 and tried again. But there is still new error message:
###
Error found by spectre during SpectreHDL compile.
   ……
       line 41:  Error: analog operator `ddt' embedded in conditionally
       executed statement or expression.
###

Now, I am confused about that, what's wrong?  
My icfb version is  5.1.0 02/01/2005.

The following are only some lines of your codes.
Code:

....
analog begin
	vmax = max(abs(vdd),abs(vss));
	g = 5*ln(n);
	@(cross(V(pin,nin) - thresh, 0));

	// hold capacitor with capacitance tt
	I(vg,hold) <+ tt*ddt(V(vg,hold));

	// clamp hold capacitor during dc analysis
	if (analysis("static"))
	    I(vg,hold) <+ V(vg,hold);
		    ...