I was bored and found a HP-27S

[Thomas Radtke]

(06-10-2014 07:19 PM)Katie Wasserman Wrote:  

(06-10-2014 04:06 PM)Thomas Radtke Wrote:  It is programmable, the solver is just not turing complete. Calculators like the 20S play in the same league, allthough not as obvious.

"not Turing Complete", I think not!

I assumed some kind of array would be required, but I was wrong (at least on the 20S), sorry.

Not being an expert with the solver, I tried to construct an infinite loop this morning:

(1) A=sigma(I:1:10:0:I) gives 'solution not found'

(2) A=sigma(I:1:10:1:L(I:I-1)) gives 45

In (2), it appears, 'I' cannot be decremented and L(I:I-1) evaluates to I-1. Further investigating this:

(3) A=sigma(I:1:10:1:L(I:I-1)+I) gives 100 (apparently 45+55)

Sorry again if I've just shown my ignorance ;-/.

(feel free to fork this into another thread if it's of any interest)