some comments

python/damask/orientation.py

@@ -20,7 +20,8 @@ class Quaternion:
     Convention 4: Euler angle triplets are implemented using the Bunge convention,
                   with the angular ranges as [0, 2π],[0, π],[0, 2π]
     Convention 5: the rotation angle ω is limited to the interval [0, π]
-
+    Convention 6: P = 1 (as default)
+    
     w is the real part, (x, y, z) are the imaginary parts.
 
     Vector "a" (defined in coordinate system "A") is passively rotated

src/quaternions.f90

@@ -31,6 +31,7 @@
 !> @author Marc De Graef, Carnegie Mellon University
 !> @author Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
 !> @brief general quaternion math, not limited to unit quaternions
+!> @details  w is the real part, (x, y, z) are the imaginary parts.
 !---------------------------------------------------------------------------------------------------
 module quaternions
  use prec, only: &
@@ -39,7 +40,7 @@ module quaternions
  implicit none
  public
  
- real(pReal), parameter, public :: epsijk = -1.0_pReal                                              !< parameter for orientation conversion. ToDo: Better place?
+ real(pReal), parameter, public :: epsijk = -1.0_pReal                                              !< parameter for orientation conversion.
  
  type, public :: quaternion
    real(pReal) :: w = 0.0_pReal

src/rotations.f90

@@ -33,6 +33,16 @@
 !> @brief rotation storage and conversion
 !> @details: rotation is internally stored as quaternion. It cabe inialized from different 
 !> represantations and also returns itself in different representations.
+!
+!  All methods and naming conventions based on Rowenhorst_etal2015
+!    Convention 1: coordinate frames are right-handed
+!    Convention 2: a rotation angle ω is taken to be positive for a counterclockwise rotation
+!                  when viewing from the end point of the rotation axis towards the origin
+!    Convention 3: rotations will be interpreted in the passive sense
+!    Convention 4: Euler angle triplets are implemented using the Bunge convention,
+!                  with the angular ranges as [0, 2π],[0, π],[0, 2π]
+!    Convention 5: the rotation angle ω is limited to the interval [0, π]
+!    Convention 6: epsijk/P = -1
 !---------------------------------------------------------------------------------------------------
 
 module rotations