monte carlo and distribution functions

All,

If I read section 10.3 of the LRM, each of the distribution system 
functions allows an optional parameter type_string. An explanation at the 
end of the section explains what this type_string does, but it says 
nowhere what happens if the type_string is omitted. Does it default to 
"global" or to "instance"?

Moreover, when I read through the explanation on the type string, I find 
the wording rather vague, and it revolves around the meaning of 
"instance". When I define a module that uses the $rdist_normal function 
twice, does an instance refer to an instance of the $rdist_normal function 
(which is normally called a "call" not an "instance") or does instance 
refer to an instantiation of the module? For Monte Carlo simulations I do 
hope it is the first...

module test_dist (a, b, c);
inout a, b, c;
electrical a, b, c;
parameter integer seed = 1;

integer iseed;

analog begin

  @(initial_step) iseed = seed;

  V(a, b) = 1 + $rdist_normal(iseed, 0, 2e-02, "instance");
  V(a, c) = 1 + $rdist_normal(iseed, 0, 2e-02, "instance");

end;

endmodule; // test_dist

module tb_test_dist;

electrical a, b, c;
ground gnd;

TestMe test_dist(gnd, b, c);
R1 #(.r(1k)) resistor (b, gnd); // So are the voltages over both resistors 
the same?
R2 #(.r(1k)) resistor (c, gnd);

endmodule; // tb_test_dist


Marq Kole
Competence Leader Analog Simulation, Philips ED&T

Building WAY 3.069, Professor Holstlaan 4,5656 AA Eindhoven, The 
Netherlands
Tel. +31 40 27 44875, Fax. +31 40 27 44700
marq.kole@philips.com, www.research.philips.com