iFit/sw_mattype

 determines the type of square input matrix

 type = SW_MATTYPE(mat, {epsilon}) 

 The function determines the type of the mat 3x3xN matrix and returns a
 vector with dimensions of [1 N].

 Input:

 mat       Matrix with dimensions of [3 3 N].
 epsilon   Error bar on small matrix element. Defult is 1e-5.
           Optional.

 Output:

 type      1   Heisenberg exchange
           2   Anisotropic exchange
           3   DM interaction
           4   General matrix

 Also works on symbolic matrices, but keep all symbols real for consistent
 result!