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.
Function tables give a clear idea about the function. It makes the graphical representation of the function quite easy. In fact, it is essential to make a function table in order to draw its graph. A linear function is a mathematical equation having one independent and one dependent variable.