SolarSchwarzschildRadius is a physical constant.

WeakMixingAngle is a physical constant.

AbsIJK[q] gives the absolute value of the pure quaternion part of q.

AdjustedSignIJK[q] gives the sign of the pure quaternion part of q, adjusted so its first nonzero component is positive.

IntegerQuaternionQ[q] gives True if q is an integer quaternion and False otherwise.

LeftGCD[a, b] gives the greatest common left divisor of the quaternions a and b.

PrimaryLeftAssociate[q] gives the left associate of the quaternion q with the largest scalar component.

PrimaryRightAssociate[q] gives the right associate of the quaternion q with the largest scalar component.

Quaternion[a, b, c, d] represents the quaternion a + I b + J c + K d.

QuaternionQ[q] gives True if q is a quaternion and False otherwise.