def partsphere(self, x):
        """Sphere (squared norm) test objective function"""
        self.counter += 1
        # return np.random.rand(1)[0]**0 * sum(x**2) + 1 * np.random.rand(1)[0]
        dim = len(x)
        x = array([x[i % dim] for i in xrange(2 * dim)])
        N = 8
        i = self.counter % dim
        # f = sum(x[i:i + N]**2)
        f = sum(x[np.random.randint(dim, size=N)]**2)
        return f
Sphere (squared norm) test objective function