Date addition: can it be done in a single HP 65 program card?

[Don Shepherd]

(01-02-2020 01:38 PM)Dave Britten Wrote:  The presence of the mod operator worries me a bit

I implemented the g() function on the 65 years ago, and I handled the mod 12 for m like this:

rcl 3 (m)
9
+
12
/
frac
12
x
sto 3

that seemed to work fine. I always double-checked my test results with the 12c DAYS function and the 17b DAYS function.

Yes, I see those two large integer constants in the d() calculation, perhaps just store those in registers prior to executing the program, although you hate to have that dependency. I would imagine two cards would be required, maybe even three. My DBD program on the 65 is 96 lines.

Interesting challenge.

Don