'Sets the (flattened, log-transformed) non-fixed hyperparameters.
Parameters
theta : array, shape (n_dims,)
The non-fixed, log-transformed hyperparameters of the kernel'

@theta.setter
def theta(self, theta):

    k_dims = self.k1.n_dims
    for (i, kernel) in enumerate(self.kernels):
        kernel.theta = theta[(i * k_dims):((i + 1) * k_dims)]
