code: def test_SPDN_sparse_matmul_forward_gpu(self):
      a = cuda.to_gpu(self.a)
      b = cuda.to_gpu(self.b)
      if self.a_dtype == numpy.float16 or self.b_dtype == numpy.float16:
          self.check_SPDN_forward(a, b, atol=1e-3, rtol=1e-3)
      else:
          self.check_SPDN_forward(a, b)
  
imports: import unittest
  import numpy
  import chainer
  from chainer import cuda
  import chainer.functions
  from chainer import gradient_check
  from chainer import testing
  from chainer.testing import attr
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 6 for calling the TestCooMatMul obj's underlying member method code with example usage: obj.test_SPDN_sparse_matmul_forward_gpu() without return types