I just found a usage for the `*&` idiom
ndarray (and probably nalgebra too, but I haven't checked) provides operators, including in-place operators, but the problem is that in-place operators must be applied to assignable LHS, and assignable LHSes do not include method calls. So this, for example, does not compile:
arr.column_mut(1) += 1;
You can solve this by importing std::ops::AddAssign and doing:
arr.column_mut(1).add_assign(1);
But this loses the nicety of the operator.
Today I thought that because dereferenced place is an assignable LHS, we can do this weird thing:
*&mut arr.column_mut(1) += 1;