Function Reference
— Built-in Function: I (x)
— Built-in Function: I (n, m)
— Built-in Function: I (n, m, k, ...)
— Built-in Function: I (..., class)

Return a matrix or N-dimensional array whose elements are all equal to the pure imaginary unit, defined as Since I (also i, J, and j) is a function, you can use the name(s) for other purposes.