What is the process for returning a double* struct in Dymola from an external C code?

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To return a double* struct from an external C code in Dymola, you can follow these steps:

1. Define the struct in Dymola using the following syntax:

type MyStruct
  Real x[2];
  Real y[2];
end MyStruct;

1. In the external C code, create a function that returns a pointer to the struct. You can use the malloc() function to allocate memory for the struct on the heap.

MyStruct* getMyStruct() {
  MyStruct* ptr = (MyStruct*) malloc(sizeof(MyStruct));

  ptr->x[0] = 1.0;
  ptr->x[1] = 2.0;
  ptr->y[0] = 3.0;
  ptr->y[1] = 4.0;

  return ptr;
}

1. Add an external function declaration in Dymola to call the C function and return the struct.

external "C" MyStruct* getMyStruct();

1. Now you can use the external function in your Dymola model to get the values of the struct.

MyStruct* structPtr = getMyStruct();

Real x1 = structPtr.x[0];
Real x2 = structPtr.x[1];
Real y1 = structPtr.y[0];
Real y2 = structPtr.y[1];