Number conversion from BigDecimal to double does not work for Varargs Varargs are explained in http://java.sun.com/j2se/1.5.0/docs/guide/language/varargs.html Code Example: // C.java public class C { public static void m(double... d) { } } // T.groovy C.m(0.5, 0.5) Error: Caught: java.lang.IllegalArgumentException: argument type mismatch at T.run(T.groovy:2) at T.main(T.groovy)