Null space (or kernel) and image of a matrix

Hello!

Does anyone now if there exist a function that would compute a "null space" 
(or "kernel" - "Ker") of a matrix and maybe also one that would compute an 
"image" ("Im") of a matrix.

I tried R-site search and google, However I found notnihg useful!

Thanks for any sugestions! I am also not sure what an "image" of a matrix 
is, so suggestion in this directions  would also be  apreciated.

Ale? ?iberna