Polynomial Equations

1 PolynomialEvaluator

PolynomialEvaluator is a restricted class of block kind since both public variables have specified causality input or output.

block PolynomialEvaluator parameter Real c[:]; input Real x; output Real y; protected parameter Integer n = size(c, 1) - 1; Real xpowers[n + 1]; equation xpowers[1] = 1; for i in 1:n loop xpowers[i + 1] = xpowers[i]*x; end for; y = c[1] * xpowers[n + 1]; end PolynomialEvaluator;

You can for example use this class to evaluate a simple polynomial in terms of the built-in variable time, by instantiating the class with the coefficient vector
c = {1, 2, 3, 4}.

class PolyEvaluate1 Real p; PolynomialEvaluator polyeval(c = {1, 2, 3, 4}); equation polyeval.x = time; p = polyeval.y; // p gets the result end PolyEvaluate1;

An alternative way is to bind the inputs and the outputs using modifier equations in the declaration of the polyeval instance of PolynomialEvaluator.

class PolyEvaluate2 Real p; PolynomialEvaluator polyeval(c = {1, 2, 3, 4}, x = time, y = p); end PolyEvaluate2;

2 Simulation of PolynomialEvaluator

Here the simulation of the PolyEvaluate1 is shown. The variables can then be plotted as below.

simulate( PolyEvaluate1, stopTime=10 )
plot( p )

Here the simulation of the PolyEvaluate2 is shown.

simulate( PolyEvaluate2 )
plot( p )