Solved by ptrblck in post #3 
              
              
                Complex modules are not fully supported yet and you could thus try if the modules you want to use would already work. E.g. GRU seems to work on the CPU already: 
rnn = nn.GRU(10, 20, 2).to(torch.complex64)
input = torch.randn(5, 3, 10).to(torch.complex64)
h0 = torch.randn(2, 3, 20).to(torch.complex6…