Function array2_to_csc_with_tolerance 

pub fn array2_to_csc_with_tolerance<T: Scalar + Clone + Field>(
    arr: &Array2<T>,
    tolerance: Option<<T as Scalar>::Real>,
) -> CscMatrix<T>

Converts a dense Array2 to CSC (Compressed Sparse Column) format, with an explicit, opt-in tolerance for approximate sparsification.

Arguments

• arr - Dense 2D array
• tolerance - None selects exact-zero sparsification (see array2_to_csc). Some(tol) explicitly opts into dropping any entry with abs(value) <= tol; this must be a deliberate, user-supplied choice, never a silent default, because it changes the numerical content of the matrix.

NaN entries are always retained (stored explicitly) regardless of tolerance, since a NaN is technically non-zero and silently discarding it would be data corruption.

Returns

CSC matrix containing the retained entries