1.6 The Notation for the Imaginary Unit
Mathematica uses the letter I ( in the notebook front end) for the imaginary unit, , which is not the standard notation in the control literature. However, it is quite easy to set things up differently. Recall that the expression 2 + 3I, for example, is a shortcut for Complex[2, 3]. Therefore, to change the appearance of complex numbers, it is sufficient to change the formatting rule for Complex, as it is done in the following few lines. You may want to add an analogous definition to your init.m file if you prefer an alternative to the built-in notation.
This changes the way complex numbers appear on the screen.
From now on, appears as the letter .