HP-11C and complex numbers


Hi all.
In this period I am exploring the interesting world of the calculator emulators, in particular for my new Android phone.
It is fascinating being able to retrace decades of development with the various models.
In these days I found a nice HP-11C emulator for Android, and I am trying to discover the main differences respect to the 15C, that I know a bit better. I also downloaded the original manual, but I still have a doubt, concerning the handling of complex numbers.
I see that the 11C, as the bigger sister, has the (i) and I functions, (over the COS and TAN keys), but I did not understand their use, because it seems that it doesn't have a Commplex Mode as in the 15C.
Could you please clarify this issue?


The 11C does not do complex arithmetic. I and (i) are used for indirect addressing exclusively.


Register I is also used for loop control.


Both ISG and DSE work only with register I.




Have a look on the compare features function on this site:
HP-11C vs. HP-15C


Thanks to all for the fast answers,
now I understand better the differences between the two models concerning complex numbers, and will try to study the question of indirect addressing with (i) and I.

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