imaginary unit (i) position on key

[hpprime123]

Keys priority depends on user. My opinion is that the keys should be where the user thinks they should be.

(), [], {} on the same key.
Point (.), comma (,) on the same key.
Enter, Equal(=)
+/- key, should be on the numeric keypad.
...

The text entry in the style of smartphons (not with keys).
Also, I miss keys to move the stack (I like rpn).

Excellent calculator with poor key assignments