(sw-mattype)=

# sw_mattype

## Syntax
  
`type = sw_mattype(mat)`
  
`type = sw_mattype(mat,epsilon)`
 
## Description
  
`type = sw_mattype(mat)` determines the type of the input matrix `mat`
which stacked $[3\times 3]$ matrices. It determines the type of exchnge
interaction that the matrix belongs to.
  
{% include note.html content=" Also works on symbolic matrices, but keep all symbols real for consistent
result!" %}
 
## Input Arguments
  
`mat`
: Matrix with dimensions of $[3\times 3\times N]$.
  
`epsilon`
: optional error bar on small matrix elements, default value is $10^{-5}$.
  
## Output Arguments
  
`type`
: Row vector with $N$ elements each having one of the following value:
  * `1`   Heisenberg exchange,
  * `2`   anisotropic exchange,
  * `3`   DM interaction,
  * `4`   general matrix.
 
*[DM]: Dzyaloshinskii-Moriya