Function Call

1 Polynomial Evaluator

There are two basic forms a of function call in Modelica: positional or named association to formal parameters. We will as an example use the function PolynomiaEvaluator, which computes the value of a polynomial given two arguments: a coefficient vector A and a value of x.

function PolynomialEvaluator input Real A[:]; // Array, size defined at function call time input Real x := 1.0; // Default value 1.0 for x output Real sum; protected Real xpower; algorithm sum := 0; xpower := 1; for i in 1:size(A, 1) loop sum := sum + A[i]*xpower; xpower := xpower*x; end for; end PolynomialEvaluator;

2 Positional Call

Function calls with positional association of actual arguments to formal parameters is the most common form of function call. The actual arguments are associated with the formal parameters according to their position in the argument list.

Using positional association {1, 2, 3, 4} becomes the value of the coefficient vector A and 21 becomes the value of the formal parameter x.

class PositionalCall Real p; equation p = PolynomialEvaluator({1, 2, 3, 4}, 21); end PositionalCall;

3 Simulation of PositionalCall

simulate( PositionalCall)
//p[0] is replaced by the following line. val (p, 0)
plot(p)

4 Named Call

The same call to the function PolynomialEvaluator can instead be made using named association of actual arguments to formal parameters. Here the actual argument is associated with the formal parameter through an equation in the argument list.

class NamedCall Real p; equation p = PolynomialEvaluator(A = {1, 2, 3, 4}, x = 21); end NamedCall;

5 Simulation of NamedCall

simulate( NamedCall )
plot(p)

Direct positionalcall:

PolynomialEvaluator({1, 2, 3, 4}, 21)