libgfx: Matrix Math
Author: Michael Garland

## Matrix Math

### class Mat3

This class implements a 3x3 real-valued matrix. Individual elements are represented with `double` precision floating point numbers. To use the `Mat3` class you must include the header

        #include <gfx/mat3.h>

#### Constructor Methods

The `Mat3` class defines the following set of constructors:

        // Initialize all elements to 0
        Mat3();

        // Initialize rows with given vectors
        Mat3(const Vec3& r0,const Vec3& r1,const Vec3& r2);

        // Copy values from A
        Mat3(const Mat3& A);