Skip to content

Fix missing device in FixCom and get_centers_of_mass() #583

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
sklenard wants to merge 1 commit into
base: main
Choose a base branch
from
+34 −19
Open

Fix missing device in FixCom and get_centers_of_mass() #583

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
43 changes: 28 additions & 15 deletions torch_sim/constraints.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -544,7 +544,9 @@ def get_removed_dof(self, state: SimState) -> torch.Tensor:
Returns:
Always returns 3 (center of mass translation degrees of freedom)
"""
affected_systems = torch.zeros(state.n_systems, dtype=torch.long)
affected_systems = torch.zeros(
state.n_systems, dtype=torch.long, device=state.device
)
affected_systems[self.system_idx] = 1
return 3 * affected_systems

Expand All @@ -559,24 +561,29 @@ def adjust_positions(self, state: SimState, new_positions: torch.Tensor) -> None
raise ValueError("FixCom requires state with system_idx")
system_idx = state.system_idx
dtype = state.positions.dtype
system_mass = torch.zeros(state.n_systems, dtype=dtype).scatter_add_(
0, system_idx, state.masses
)
device = state.device
system_mass = torch.zeros(
state.n_systems, dtype=dtype, device=device
).scatter_add_(0, system_idx, state.masses)
if self.coms is None:
self.coms = torch.zeros((state.n_systems, 3), dtype=dtype).scatter_add_(
self.coms = torch.zeros(
(state.n_systems, 3), dtype=dtype, device=device
).scatter_add_(
0,
system_idx.unsqueeze(-1).expand(-1, 3),
state.masses.unsqueeze(-1) * state.positions,
)
self.coms /= system_mass.unsqueeze(-1)

new_com = torch.zeros((state.n_systems, 3), dtype=dtype).scatter_add_(
new_com = torch.zeros(
(state.n_systems, 3), dtype=dtype, device=device
).scatter_add_(
0,
system_idx.unsqueeze(-1).expand(-1, 3),
state.masses.unsqueeze(-1) * new_positions,
)
new_com /= system_mass.unsqueeze(-1)
displacement = torch.zeros(state.n_systems, 3, dtype=dtype)
displacement = torch.zeros(state.n_systems, 3, dtype=dtype, device=device)
displacement[self.system_idx] = (
-new_com[self.system_idx] + self.coms[self.system_idx]
)
Expand All @@ -594,16 +601,19 @@ def adjust_momenta(self, state: SimState, momenta: torch.Tensor) -> None:
system_idx = state.system_idx
# Compute center of mass momenta
dtype = momenta.dtype
com_momenta = torch.zeros((state.n_systems, 3), dtype=dtype).scatter_add_(
device = state.device
com_momenta = torch.zeros(
(state.n_systems, 3), dtype=dtype, device=device
).scatter_add_(
0,
system_idx.unsqueeze(-1).expand(-1, 3),
momenta,
)
system_mass = torch.zeros(state.n_systems, dtype=dtype).scatter_add_(
0, system_idx, state.masses
)
system_mass = torch.zeros(
state.n_systems, dtype=dtype, device=device
).scatter_add_(0, system_idx, state.masses)
velocity_com = com_momenta / system_mass.unsqueeze(-1)
velocity_change = torch.zeros(state.n_systems, 3, dtype=dtype)
velocity_change = torch.zeros(state.n_systems, 3, dtype=dtype, device=device)
velocity_change[self.system_idx] = velocity_com[self.system_idx]
momenta -= velocity_change[system_idx] * state.masses.unsqueeze(-1)

Expand All @@ -621,18 +631,21 @@ def adjust_forces(self, state: SimState, forces: torch.Tensor) -> None:
raise ValueError("FixCom requires state with system_idx")
system_idx = state.system_idx
dtype = state.positions.dtype
system_square_mass = torch.zeros(state.n_systems, dtype=dtype).scatter_add_(
device = state.device
system_square_mass = torch.zeros(
state.n_systems, dtype=dtype, device=device
).scatter_add_(
0,
system_idx,
torch.square(state.masses),
)
lmd = torch.zeros((state.n_systems, 3), dtype=dtype).scatter_add_(
lmd = torch.zeros((state.n_systems, 3), dtype=dtype, device=device).scatter_add_(
0,
system_idx.unsqueeze(-1).expand(-1, 3),
forces * state.masses.unsqueeze(-1),
)
lmd /= system_square_mass.unsqueeze(-1)
forces_change = torch.zeros(state.n_systems, 3, dtype=dtype)
forces_change = torch.zeros(state.n_systems, 3, dtype=dtype, device=device)
forces_change[self.system_idx] = lmd[self.system_idx]
forces -= forces_change[system_idx] * state.masses.unsqueeze(-1)

Expand Down
10 changes: 6 additions & 4 deletions torch_sim/transforms.py
View file
Open in desktop

@curtischong curtischong Jul 3, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I feel like linked_cell may also need a device= arg. it'd be great if we can add it in this PR!

@curtischong curtischong Jul 3, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

https://github.com/TorchSim/torch-sim/blob/main/torch_sim/transforms.py#L891 and https://github.com/TorchSim/torch-sim/blob/main/torch_sim/transforms.py#L971

Original file line number Diff line number Diff line change
Expand Up @@ -1620,13 +1620,15 @@ def get_centers_of_mass(
torch.Tensor: A tensor of shape (n_structures, 3) containing
the center of mass coordinates for each structure.
"""
coms = torch.zeros((n_systems, 3), dtype=positions.dtype).scatter_add_(
coms = torch.zeros(
(n_systems, 3), dtype=positions.dtype, device=positions.device
).scatter_add_(
0,
system_idx.unsqueeze(-1).expand(-1, 3),
masses.unsqueeze(-1) * positions,
)
system_masses = torch.zeros((n_systems,), dtype=positions.dtype).scatter_add_(
0, system_idx, masses
)
system_masses = torch.zeros(
(n_systems,), dtype=positions.dtype, device=positions.device
).scatter_add_(0, system_idx, masses)
coms /= system_masses.unsqueeze(-1)
return coms
Loading