Problem with HCP slip systems

[MartinL75]

Hi,
I'm trying to calculate the slip systems for the HCP lattice using MTEX 5.4 in Matlab 2016b and following the documentation. However, results are confusing because the number of symmetrical systems are not correct (see code below). The expected quantity of slip systems should be 3 for basal and prismatic , and 6 for pyramidal <c+a>.
Previously I was using MTEX 5.1.1 with no trouble, but I was hoping to move to a newer version so I can use the updated plasticity functions.
Thanks a lot in advance. Regards!

Martín.-

---

CS = crystalSymmetry('6/mmm', [2.665 2.665 4.947], 'X||a*', 'Y||b', ...
      'Z||c', 'mineral', 'Zinc', 'color', 'light blue');
sS_basal = slipSystem.basal(CS)
 
sS_basal = slipSystem (show methods, plot)
 mineral: Zinc (6/mmm, X||a*, Y||b, Z||c)
 size: 1 x 1
  U    V    T    W  | H    K    I    L CRSS
  1    1   -2    0    0    0    0    1    1
 
sS_prism = slipSystem.prismaticA(CS)

sS_prism = slipSystem (show methods, plot)
 mineral: Zinc (6/mmm, X||a*, Y||b, Z||c)
 size: 1 x 1
  U    V    T    W  | H    K    I    L CRSS
  2   -1   -1    0    0    1   -1    0    1
 
sS_pirII = slipSystem.pyramidal2CA(CS)

sS_pirII = slipSystem (show methods, plot)
 mineral: Zinc (6/mmm, X||a*, Y||b, Z||c)
 size: 1 x 1
  U    V    T    W  | H    K    I    L CRSS
  2   -1   -1    3   -2    1    1    2    1


sS_basal_sym = sS_basal.symmetrise('antipodal')

sS_basal_sym = slipSystem (show methods, plot)
 mineral: Zinc (6/mmm, X||a*, Y||b, Z||c)
 **size: 5 x 1**
   U    V    T    W  | H    K    I    L CRSS
   1   -2    1    0    0    0    0    1    1
  -1   -1    2    0    0    0    0    1    1
  -2    1    1    0    0    0    0    1    1
  -2    1    1    0    0    0    0    1    1
   1    1   -2    0    0    0    0    1    1
 
sS_prism_sym = sS_prism.symmetrise('antipodal')

sS_prism_sym = slipSystem (show methods, plot)
 mineral: Zinc (6/mmm, X||a*, Y||b, Z||c)
 **size: 5 x 1**
   U    V    T    W  | H    K    I    L CRSS
  -1   -1    2    0   -1    1    0    0    1
  -1   -1    2    0   -1    1    0    0    1
   1    1   -2    0   -1    1    0    0    1
   2   -1   -1    0    0    1   -1    0    1
   1   -2    1    0   -1    0    1    0    1
 
sS_pirII_sym = sS_pirII.symmetrise('antipodal')

sS_pirII_sym = slipSystem (show methods, plot)
 mineral: Zinc (6/mmm, X||a*, Y||b, Z||c)
 **size: 8 x 1**
   U    V    T    W  | H    K    I    L CRSS
   1   -2    1   -3   -1    2   -1   -2    1
  -1    2   -1   -3    1   -2    1   -2    1
   2   -1   -1    3   -2    1    1    2    1
   2   -1   -1   -3   -2    1    1   -2    1
  -1   -1    2   -3   -1   -1    2    2    1
   1    1   -2    3   -1   -1    2    2    1
   1    1   -2   -3    1    1   -2    2    1
  -1   -1    2    3    1    1   -2    2    1

---

[kilir]

Hi,
I think it is a rounding bug and should be fixed. You can either change the tolerance in vector3d/unique or you can make a very very tiny change to your definition of CS e.g.

CS = crystalSymmetry('6/mmm', [2.665001 2.665001 4.947001], 'X||a*', 'Y||b', ...
      'Z||c', 'mineral', 'Zinc', 'color', 'light blue');

Cheers,
Rüdiger

[MartinL75]

Thanks a lot for the quick answer, it worked.
I changed the tolerance in vector3d/unique from 1e-07 to 1e-08.
Cheers,
Martín.