I became one of the 15c collecting Crowd

[Steve Simpkin]

(10-28-2023 11:24 PM)Johnh Wrote:  ..
Interesting to hear about the results from different machines. So I tried it on my HP35s. There are two ways on this calc, either using a programmed subroutine, or using an equation. I found that the EQN method ran quicker, and in SCI 6 mode the results were:

Program method: 2 min 30 sec
EQN mode 1 min 45 sec

Both give the same result, correct to 6 decimal places as I found on the 15C, and after revealing more sig figs after the run, accurate until one digit off in the 9th decimal place.

The HP15C CE ran in 17 sec with SCI 6, and resulted in one digit off in the 7th decimal place.

So maybe there are a few differences in the algo's being used across the years, with more or fewer guard digits. But all are doing a great job at dealing with this rather crazy function and it's a testament to the very clever and adaptable numerical integration methods being used in all the hp's. At high-school we learnt about the trapezium method, and then the accuracy benefits of Simpsons method, but this seems to be a lot better again.
...

It should be noted that William Kahan was responsible for creating the underlying algorithms for the Solver and Integration functions on the HP-34C and HP-15C. He is also largely responsible for determining the advanced feature set of the HP-15C. The HP-15C team wrote the HP-15C firmware in the assembly language of the HP Nut processor used on those models.

The firmware for the HP 35s was written in C by Kinpo Electronics, who also manufactured the calculator for HP. This model uses a Sunplus/Generalplus 8502 microcontroller (with CPU core based on MOS 6502). Kinpo worked from a functional specification document provided by HP but I do not know if any elements of the original HP algorithms were used by Kinpo.

Very different animals.