Set the left 3x3 submatrix of this {@link Matrix4x3d} to the given {@link Matrix3d} and don't change the other elements.
@param mat the 3x3 matrix @return this
See Implementation
Set the left 3x3 submatrix of this {@link Matrix4x3d} to the given {@link Matrix3d} and don't change the other elements.
@param mat the 3x3 matrix @return this