Imaginary Unit - Alternative Notations

Alternative Notations

• In electrical engineering and related fields, the imaginary unit is often denoted by j to avoid confusion with electrical current as a function of time, traditionally denoted by i(t) or just i. The Python programming language also uses j to denote the imaginary unit. MATLAB associates both i and j with the imaginary unit, although 1i or 1j is preferable, for speed and improved robustness.
• Some sources define j = −i, in particular with regard to traveling waves (e.g., a right traveling plane wave in the x direction) .
• Some texts use the Greek letter iota (ι) for the imaginary unit, to avoid confusion, esp. with index and subscripts.
• Each of i, j, and k is an imaginary unit in the quaternions. In biquaternions an additional imaginary unit h is used.