sand dollar. n. 1. Any of various thin circular echinoderms of the order Clypeasteroida, especially Echinarachnius parma, of coastal northern Atlantic and Pacific waters, having a covering of short movable spines.
One reason why linear algebra is very useful is that linear transforms of normal variables are normal. If x ~ N(a, A), then Bx+b ~ N(Ba+b, BABT). In a way, when everything is linear and normal, everything is nice and analytically tractable.
Linear algebra courses run the risk of becoming a conglomeration of learn-. by-rote recipes involving arrays lled with numbers. In the modern computer. era, understanding these recipes, why they work, and what they are for is. more important than ever.