________________________ test_kernel_gradient[kernel11] ________________________
[gw1] linux -- Python 3.9.10 /home/vsts/work/1/s/testvenv/bin/python

kernel = 1.41**2 * Matern(length_scale=[0.5, 2], nu=0.5)

    @fails_if_pypy
    @pytest.mark.parametrize("kernel", kernels)
    def test_kernel_gradient(kernel):
        # Compare analytic and numeric gradient of kernels.
        K, K_gradient = kernel(X, eval_gradient=True)
    
        assert K_gradient.shape[0] == X.shape[0]
        assert K_gradient.shape[1] == X.shape[0]
        assert K_gradient.shape[2] == kernel.theta.shape[0]
    
        def eval_kernel_for_theta(theta):
            kernel_clone = kernel.clone_with_theta(theta)
            K = kernel_clone(X, eval_gradient=False)
            return K
    
        K_gradient_approx = _approx_fprime(kernel.theta, eval_kernel_for_theta, 1e-10)
    
>       assert_almost_equal(K_gradient, K_gradient_approx, 4)
E       AssertionError: 
E       Arrays are not almost equal to 4 decimals
E       
E       Mismatched elements: 8 / 75 (10.7%)
E       Max absolute difference: 71.55003086
E       Max relative difference: 0.67469822
E        x: array([[[2.0000e+000, 1.3853e-309, 9.3709e-310],
        [2.38801479e-01, 4.98647235e-01, 8.87095952e-03],
        [2.00000017e+00, 0.00000000e+00, 0.00000000e+00]]])
eval_kernel_for_theta = <function test_kernel_gradient.<locals>.eval_kernel_for_theta at 0x4c915408d50>
kernel     = 1.41**2 * Matern(length_scale=[0.5, 2], nu=0.5)