HP Prime/Commands/Guides/All About Complex Numbers
The complex data type has a type ID of 3.
One way to make complex constants is with this notation:
Where a and b are arbitrary expressions. It is translated to an expression in the following format:
This is the translation that literally happens in HPPPL; thus, type errors may occur in some cases.
Each part of a complex expression is bounded to the limits of a real. It follows the rules specified there.