A fancy uppercase H represents the ring of Hamilton Quaternions.
A quaternion takes the general form shown below:
a + bi + cj + dk
The symbols a,b,c,d represent real numbers.
The symbold i,j,k are not coordinate vectors.
a + 0i + 0j + 0k is a scalar.
a + bi + 0j + 0k is a complex number.
Quaternions provide elegant expressions for Lorentz transformations.
A Multiplication Table was found for Quaternions:
Rob Sterling 