HP 25 Fibonacci sequence in one program step

[Dave Britten]

I think you guys have figured out the gist of it.

The solution in the book is to set FIX 0, and fill the stack thusly:

T: phi
Z: phi
Y: phi
X: 1/SQRT(5)

Where phi is the golden ratio: (SQRT(5)+1)/2. The 1/SQRT(5) term is derived from Binet's formula.

Then your HP 25 program need only be:

01 *
02 GTO 00

But that that point, one scarcely needs a program at all.

The calculation gets more and more accurate with each successive term, but the FIX 0 rounding should give you a correct integer result for all terms.