(spinw-twinq)=

# spinw.twinq method

## Syntax
  
`[qTwin, rotQ] = twinq(obj, {Q0})`
  
## Description
  
`[qTwin, rotQ] = twinq(obj, {q0})` calculates the $Q$ values in the twin
coordinate systems, in rlu. It also returns the rotation matrices, that
transforms the $Q$ point from the original lattice to the selected twin
rlu coordinate system.
  
## Examples
  
This example Calculates the $[1,0,0]$ and $[1,1,0]$ Bragg reflections
equivalent positions in the twins.
 
```matlab
Q1 = [1 0 0; 1 1 0];
Q2 = cryst.twinq(Q1');
```
  
## Input Arguments
  
`Q0`
: $Q$ values in the original crystal in rlu sotred in a matrix with
dimensions of $[3\times n_Q]$, optional.
  
## Output Arguments
  
`Qtwin`
: $Q$ values in the twin oordinate system in a cell element for
          each twin.
 
`rotQ`
: Rotation matrices with dimensions of $[3\times 3\times n_{twin}]$.
  
## See Also
  
[spinw](#spinw) \| [spinw.addtwin](#spinw-addtwin)
 
*[rlu]: Reciprocal Lattice Unit