SimpleMath was based on the methods in the XNA Game Studio math classes. There are a few Quaternion functions that have been added to other math libraries that would be useful to add for Quaternion:
RotateTowards which moves a quaternion toward a target quaternion limited by a maximum delta angle
FromToRotation which computes a relative rotation between two direction vectors
LookRotation which computes a rotation which aligns to a direction and up vector
Angle which computes the angle between two quaternion rotations
SimpleMath was based on the methods in the XNA Game Studio math classes. There are a few Quaternion functions that have been added to other math libraries that would be useful to add for Quaternion:
RotateTowardswhich moves a quaternion toward a target quaternion limited by a maximum delta angleFromToRotationwhich computes a relative rotation between two direction vectorsLookRotationwhich computes a rotation which aligns to a direction and up vectorAnglewhich computes the angle between two quaternion rotations