### Question:
NewtonDefaultUpdateFunction implements NewtonRootFinderMatrixUpdateFunction { @Override public DoubleMatrix getUpdatedMatrix( Function<DoubleArray, DoubleMatrix> jacobianFunction, DoubleArray x, DoubleArray deltaX, DoubleArray deltaY, DoubleMatrix matrix) { ArgChecker.notNull(jacobianFunction, "jacobianFunction"); ArgChecker.notNull(x, "x"); return jacobianFunction.apply(x); }  @Override DoubleMatrix getUpdatedMatrix(
      Function<DoubleArray, DoubleMatrix> jacobianFunction,
      DoubleArray x,
      DoubleArray deltaX,
      DoubleArray deltaY,
      DoubleMatrix matrix);  }### Answer:
@Test public void testNullFunction() { assertThatIllegalArgumentException() .isThrownBy(() -> F.getUpdatedMatrix(null, null, null, null, null)); }
@Test public void testNullVector() { assertThatIllegalArgumentException() .isThrownBy(() -> F.getUpdatedMatrix(new Function<DoubleArray, DoubleMatrix>() { @Override public DoubleMatrix apply(DoubleArray x) { return null; } }, null, null, null, null)); }