Function fold_cols 

pub fn fold_cols<F, DataMat, DataVec>(
    mat: &FieldBuffer<F, DataMat>,
    vec: &FieldBuffer<F, DataVec>,
) -> FieldBuffer<F>
where
    F: Field,
    DataMat: Deref<Target = [F]>,
    DataVec: Deref<Target = [F]>,

Computes a linear combination of the columns of a matrix.

A column-combination of a matrix is a matrix-vector multiplication.

This implementation is a naive, single-threaded implementation operating on buffers of scalar elements.

Mathematical Definition

This operation accepts

• $n \in \mathbb{N}$ (out.len()),
• $m \in \mathbb{N}$ (vec.len()),
• $M \in K^{n \times m}$ (mat),
• $v \in K^m$ (vec),

and computes the vector $Mv$.

Args

• mat - a buffer of n * m F elements, interpreted as a row-major matrix.
• vec - a buffer of m F elements containing the column scalars.

Returns

The matrix-vector product, as a buffer of F elements.

Preconditions

• mat.log_len() must be at least vec.log_len()