Matrix2 class

Represents a 2x2 matrix.

A Note on Row-Major and Column-Major Ordering:

The constructor and {@link Matrix2#set} method take arguments in row-major{@link https://en.wikipedia.org/wiki/Row-_and_column-major_order#Column-major_order} order, while internally they are stored in the {@link Matrix2#elements} array in column-major order. This means that calling:

const m = new THREE.Matrix2();
m.set( 11, 12,
       21, 22 );

will result in the elements array containing:

m.elements = [ 11, 21,
               12, 22 ];

and internally all calculations are performed using column-major ordering. However, as the actual ordering makes no difference mathematically and most people are used to thinking about matrices in row-major order, the three.js documentation shows matrices in row-major order. Just bear in mind that if you are reading the source code, you'll have to take the transpose of any matrices outlined here to make sense of the calculations.