Fix acoustic tests

Author: ar4

tests/test_acoustic.py

@@ -236,11 +236,13 @@ def test_forward_cpu_gpu_match() -> None:
                 propagator=acousticprop,
                 device=torch.device("cpu"),
                 prop_kwargs={"python_backend": python},
+                dtype=torch.double,
             )
             actual_gpu = run_forward(
                 propagator=acousticprop,
                 device=torch.device("cuda"),
                 prop_kwargs={"python_backend": python},
+                dtype=torch.double,
             )
             for cpui, gpui in zip(actual_cpu, actual_gpu):
                 assert torch.allclose(cpui, gpui.cpu(), atol=5e-5)
@@ -318,6 +320,8 @@ def test_unused_source_receiver(
         torch.manual_seed(1)
         if device is None:
             device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
+        if dtype is None:
+            dtype = torch.double
 
         if prop_kwargs is None:
             prop_kwargs = {}
@@ -892,7 +896,7 @@ def run_gradcheck(
     )
 
     if isinstance(rho_val, torch.Tensor):
-        rho = rho_val.to(device)
+        rho_val = rho_val.to(device)
     rho = (
         torch.ones(*nx, device=device, dtype=dtype) * rho_val
         + torch.rand(*nx, device=device, dtype=dtype) * drho