code: def test_computes_linear_function_rectangular(self):
      a = torch.tensor([4, 2, 8], dtype=torch.float).view(3, 1)
      b = torch.tensor([0, 2, 1], dtype=torch.float).view(3, 1)
  
      kernel = LinearKernel().initialize(variance=1.0)
      kernel.eval()
      actual = torch.matmul(a, b.t())
      res = kernel(a, b).to_dense()
      self.assertLess(torch.norm(res - actual), 1e-4)
  
      # diag
      res = kernel(a, b).diagonal(dim1=-1, dim2=-2)
      actual = actual.diagonal(dim1=-1, dim2=-2)
      self.assertLess(torch.norm(res - actual), 1e-4)
  
file_path: gpytorch/test/kernels/test_linear_kernel.py
imports: import unittest
  import torch
  from gpytorch.kernels import LinearKernel
  from gpytorch.priors import NormalPrior
  from gpytorch.test.base_kernel_test_case import BaseKernelTestCase
label_desc: Use image node_id 2 for calling the TestLinearKernel obj's underlying member method code with example usage: obj.test_computes_linear_function_rectangular() without return types