Math namespace Question

dear
i would like to ask questions regarding the core of opentk.

1- the Math nameaspace contains implementations for the matrixes and verctors used allover opentk. all these types are implemented as structures rather than classes, the question is why?. all this copying of structures that may results in a memory overhead.

2-the matrix structure of the Math nameaspace (matrix4d) implements a transformaton matrix with last row as the translation vector rather than the last column which is opposite to the conventions used in literature. so why?.

best regards