Function sub_vol_assign 

pub fn sub_vol_assign<T>(
    backend: ComputeBackend,
    y: &mut VolField<T>,
    x: &VolField<T>,
)
where
    T: Copy + Send + Sync + Sub<Output = T>,

In-place subtraction on a volume field, y -= x. Allocation-free, name-preserving.

Units: y and x are the same physical quantity.

Panics

Panics if the internal fields or any patch pair differ in length.