modular exponentiation?

[John Keith]

(06-24-2018 09:18 AM)Didier Lachieze Wrote:  On the HP Prime in CAS mode:
\[\LARGE irem( \sum_{n=1}^{1000} (powmod(n,n,10^{10})), 10^{10})\]
or, if you want to copy/paste to the emulator:

irem(Σ(powmod(n,n,10^10),n,1,1000),10^10)

Wow, almost instantaneous!

My HP 50 version,

Code:


\<< PUSH CASDIR MODULO \-> m
  \<< 10 DUP ^ MODSTO 0 1 1000
    FOR n n DUP POWMOD
      IF DUP 0 <
      THEN MODULO +
      END +
    NEXT MODULO MOD m MODSTO POP
  \>>
\>>

is rather slow and clunky due to the HP 50's quirky POWMOD function. It takes about 130 seconds to run, or about 2.5 seconds on the emulator.

John