Questions about if, when, while statements

Question

I would like to write a loop whose function is that when the value of c is less than 0.1, the loop terminates and outputs the value at the moment. Here's the code I wrote, I don't know when or while to use, thanks in advance for your reply

model Unnamed
 Real a;
 Real b;
 Real c(start=2);

algorithm 


 while abs(c)>0.1 loop
  a:=2*time-0.5;
  b:=time+0.1;
  c:=a-b;
 //  break;
 end while;

end Unnamed;

Answer 1

As far as I understand the algorithm and while-loop isn't important.

What you want is to simulate as long as abs(c)>0.1 and then stop!

That can be done as follows:

model Unnamed
 Real a;
 Real b;
 Real c(start=2);
algorithm 
 a:=2*time-0.5;
 b:=time+0.1;
 c:=a-b;
 when not abs(c)>0.1 then
   terminate("Reached end");
 end when;
end Unnamed;

This will stop after 0.5s. And as @marco noted it is generally preferable to use an equation instead of an algorithm - so just write:

model Unnamed
 Real a;
 Real b;
 Real c(start=2);
equation 
 a=2*time-0.5;
 b=time+0.1;
 c=a-b;
 when not abs(c)>0.1 then
   terminate("Reached end");
 end when;
end Unnamed;