Quaternion unity, and operators i, j and k
q1/qi/qj/qk
These four functions return constant quaternions with values corresponding to unity and the three quaternion operators i, j and k.
In versions of the toolbox prior to 2.5, the q1 function returned the same value as the current function qi.
The symbol i is a builtin MATLAB® operator for the complex root of -1, and therefore it cannot be used for the quaternion i. This is why the notation qi is used.
>> q1 + qi + qj + qk ans = 1 + 1 * I + 1 * J + 1 * K