You can store your own operations in macros. See Macros. Similarly, you can create custom matrix operations. For example, you can make your own matrix operation called Mag() to find the magnitude of a vector, as follows:
mag = Function( {x},
Sqrt( x` * x )
);
Similarly, you could create an operation called Normalize to divide a vector by its magnitude, as follows:
normalize = Function( {x},
x / Sqrt( x` * x )
);