VectorRhsODE.groovy

## VectorRhsODE.groovy
@ComponentInfo(name="VectorRhsODE", category="ODE")
public class VectorRhsODE implements Serializable, VectorRhsODEInterface {

    private static final long serialVersionUID = 1L;
    private transient Script script;

    @MethodInfo(name="", valueName="", valueStyle="default", valueOptions="", hide=false)
    public VectorRhsODEInterface setExpression(
        @ParamInfo(name="<html><b>Vector-valued Function f(t,u)</b>: <br>Param: double t, double[] <b>u</b><br>Return: double[] <b>f</b></hmtl>", style="code", options="") String expression) {
        GroovyShell shell = new GroovyShell();
         script = shell.parse("import static java.lang.Math.*;"
                            + "import eu.mihosoft.vrl.types.*;"
                            + "f = new double[u.length];"
                            + expression);
        return this;
    }

    @MethodInfo(name="", valueName="", valueStyle="array", valueOptions="", hide=true)
    public double[] run(
        @ParamInfo(name="t", style="", options="") double t,
        @ParamInfo(name="u", style="array", options="") double[] u) {

        if(script != null){
          script.setProperty("u", u);
          script.setProperty("t", t);
          script.run();
          return (double[]) script.getProperty("f");
        } else {
          throw(new RuntimeException("No user function specified."));
        }
    }
}