Hi I am trying to do a value assignment in AIMMS. Here is the example:

t and i are both the index of set time. n and r are the index for set Node. NodeInTime, needed_value are predetermined parameters. scenario is parameter changing in the process. noted_scenarios_index is a subset of Node. path is a mapping between index (r,t) and set Node.

for (n,t)| t<>first(time) and n<=NodeInTime(t) do

   scenario := 1;

   noted_scenarios_index := {r | r <= NodeInTime(t) and path(r, t) = n};

   for r in noted_scenarios_index do

        needed_value(scenario, n, t, i) := value(path(r,i), i);

        scenario := scenario + 1;

   endfor;

endfor;

I used debug move to check and surprisingly, the slowest part is:

needed_value(scenario, n, t, i) := value(path(r,i), i);

when it runs to this line, ‘scenario’, ‘n’, ‘t’ are determined and it took more than 30s to run this line….. So I don’t understand why it’s so slow.

I also tried using an additional parameter like:

addition(i) := value(path(r,i), i);

needed_value(scenario, n, t, i) := addition(i);

and  addition(i) := value(path(r,i), i); runs quite fast.

However, needed_value(scenario, n, t, i) := addition(i); still runs very slow.

Can you give me some suggestion on how to improve the assignment speed?