Is there a way to use a matrix larger than 4x4?

I need to create matrices that are larger then mat4. (ex: 7x7, 7x6) and apply functions such as transpose and inverse as well as multiplications with vectors (ex: vec7, vec6).

Is there a way to implement a matrix and vector that are bigger than what is provided?

I have tried the following:

1.

typedef mat<6, 6, float, defaultp>  mat6;

This gives me "Implicit instantiation of undefined template"

2. I'm pretty sure I can use several smaller matrices and kind of assume they are together but this makes the code hard to understand for others and becomes very messy.