Sorting in Modelica

In Modelica, we don’t have built-in sorting capabilities like in some other languages. However, we can implement a simple sorting algorithm to demonstrate the concept. We’ll use a bubble sort algorithm for this example.

model Sorting
  function bubbleSort
    input Real[:] arr;
    output Real[:] sortedArr;
  protected 
    Real temp;
    Integer n = size(arr, 1);
    Real[:] workArr = arr;
  algorithm
    for i in 1:n-1 loop
      for j in 1:n-i loop
        if workArr[j] > workArr[j+1] then
          temp := workArr[j];
          workArr[j] := workArr[j+1];
          workArr[j+1] := temp;
        end if;
      end for;
    end for;
    sortedArr := workArr;
  end bubbleSort;

  function printArray
    input Real[:] arr;
  algorithm
    for i in 1:size(arr, 1) loop
      Modelica.Utilities.Streams.print(String(arr[i]) + " ");
    end for;
    Modelica.Utilities.Streams.print("\n");
  end printArray;

  Real[3] strs = {3, 1, 2};  // Using numbers instead of strings
  Real[3] ints = {7, 2, 4};
  Real[3] sortedStrs;
  Real[3] sortedInts;
equation
  sortedStrs = bubbleSort(strs);
  sortedInts = bubbleSort(ints);
algorithm
  Modelica.Utilities.Streams.print("Numbers: ");
  printArray(sortedStrs);
  
  Modelica.Utilities.Streams.print("Ints:    ");
  printArray(sortedInts);
  
  Modelica.Utilities.Streams.print("Sorted:  " + String(sortedInts[1] <= sortedInts[2] and sortedInts[2] <= sortedInts[3]));
end Sorting;

In this Modelica example:

1. We define a bubbleSort function that implements the bubble sort algorithm. This function takes an array of Real numbers as input and returns the sorted array.

2. We also define a printArray function to help us print the contents of an array.

3. In the main model, we create two arrays: strs and ints. Note that Modelica doesn’t have a built-in string type, so we’re using numbers instead of strings for the first array.

4. We use the bubbleSort function to sort both arrays.

5. We then print the sorted arrays using our printArray function.

6. Finally, we check if the sortedInts array is in sorted order by comparing adjacent elements.

To run this Modelica model, you would typically use a Modelica simulation environment. The output would look something like this:

Numbers: 1 2 3 
Ints:    2 4 7 
Sorted:  true

This example demonstrates a basic sorting implementation in Modelica. Unlike some other languages, Modelica doesn’t have built-in sorting functions, so we had to implement the sorting algorithm ourselves. Also, Modelica is primarily used for physical system modeling and simulation, so sorting isn’t as common an operation as it might be in general-purpose programming languages.