### Question:
Sgn extends Function { public Sgn(Generic generic) { super("sgn", new Generic[]{generic}); } Sgn(Generic generic); Generic antiDerivative(int n); Generic derivative(int n); Generic selfExpand(); Generic selfElementary(); Generic selfSimplify(); Generic selfNumeric(); String toJava(); @Nonnull Variable newInstance();  }### Answer:
@Test public void testSgn() throws Exception { final JsclMathEngine me = JsclMathEngine.getInstance(); Assert.assertEquals("1", me.evaluate("sgn(10)")); Assert.assertEquals("1", me.evaluate("sgn(0.5)")); Assert.assertEquals("0", me.evaluate("sgn(0)")); Assert.assertEquals("0", me.evaluate("sgn(-0)")); Assert.assertEquals("-1", me.evaluate("sgn(-1)")); Assert.assertEquals("-1", me.evaluate("sgn(-10)")); }