You can store your own JSL operations in macros. See “Maximize and Minimize Functions”. Similarly, you can create custom matrix functions. For example, you can make your own matrix operation called Mag() to find the magnitude of a vector:
mag = Function( {x},
Sqrt( x` * x )
);
Similarly, you could create a function called Normalize to divide a vector by its magnitude:
normalize = Function( {x},
x / Sqrt( x` * x )
);