Add comment for stride calculation in blas mat-vec mul

Comment by jturner314 in PR #585

Author: bluss

src/linalg/impl_linalg.rs

@@ -609,6 +609,10 @@ pub fn general_mat_vec_mul<A, S1, S2, S3>(
             ($ty:ty, $gemv:ident) => {
                 if let Some(layout) = blas_layout::<$ty, _>(&a) {
                     if blas_compat_1d::<$ty, _>(&x) && blas_compat_1d::<$ty, _>(&y) {
+                        // Determine stride between rows or columns. Note that the stride is
+                        // adjusted to at least `k` or `m` to handle the case of a matrix with a
+                        // trivial (length 1) dimension, since the stride for the trivial dimension
+                        // may be arbitrary.
                         let a_trans = CblasNoTrans;
                         let a_stride = match layout {
                             CBLAS_LAYOUT::CblasRowMajor => {