For in Modelica

In Modelica, loops are primarily implemented using the for construct. Let’s explore different types of loops and their usage.

model ForLoops
  parameter Integer n = 3;
equation
  // The most basic type, with a single condition
  for i in 1:3 loop
    Modelica.Utilities.Streams.print(String(i));
  end for;

  // A classic initial/condition/after loop
  for j in 0:2 loop
    Modelica.Utilities.Streams.print(String(j));
  end for;

  // Iterating over a range
  for i in 0:n-1 loop
    Modelica.Utilities.Streams.print("range " + String(i));
  end for;

  // Modelica doesn't have an exact equivalent to Go's infinite loop,
  // but you can create a loop that runs for a very long time
  for k in 1:1e6 loop
    Modelica.Utilities.Streams.print("loop");
    break;
  end for;

  // Demonstrating continue (in Modelica, it's called 'next')
  for m in 0:5 loop
    if mod(m, 2) == 0 then
      next;
    end if;
    Modelica.Utilities.Streams.print(String(m));
  end for;
end ForLoops;

In this example:

1. We use the basic for loop syntax to iterate over a range of values.

2. Modelica’s for loops are more similar to range-based for loops in other languages, where you specify a range to iterate over.

3. Modelica doesn’t have a direct equivalent to Go’s condition-only for loop, but you can achieve similar results by using a range.

4. There’s no built-in infinite loop in Modelica, but you can create a loop with a very large range to simulate one.

5. Instead of continue, Modelica uses next to skip to the next iteration.

6. Modelica doesn’t have a break statement for loops. To exit a loop early, you typically need to use a conditional statement that covers the entire loop body.

When you run this model, it will print:

1
2
3
0
1
2
range 0
range 1
range 2
loop
1
3
5

Note that Modelica is primarily used for modeling physical systems and simulations, so its looping constructs are often used differently than in general-purpose programming languages. The equation section in Modelica models is used for writing equations that describe the system’s behavior, rather than imperative statements.

Modelica also provides other ways to work with arrays and iterate over elements, which can be more appropriate in certain modeling scenarios.