5 #include "../detail/type_mat2x2.hpp"    15     typedef mat<2, 2, double, defaultp>     
dmat2x2;
    20     typedef mat<2, 2, double, defaultp>     
dmat2;
 mat< 2, 2, double, defaultp > dmat2
2 columns of 2 components matrix of double-precision floating-point numbers. 
mat< 2, 2, double, defaultp > dmat2x2
2 columns of 2 components matrix of double-precision floating-point numbers.