Re: Floating point: sine, cosine etc.

From: ruud_at_baltissen.org
Date: Sat, 24 Sep 2022 16:09:54 +0200
Message-ID: <8882e028a3a10cce646f43b9d74377eb_at_baltissen.org>
Hallo allemaal,


> Now my question: is there anybody here who knows more of the ins and
> outs of these polynomes?

Thinking things over I realized that the question may be was not 
complete. I should have added: "as used in the various Commodores".

And for MichaƂ: thank you for you answers! Already the first one gave me 
a kick to look at the problem from another angle.

For Olaf: When knowing the various tricks, converting is simple. My FP 
numbers are 128 bits: 16 for the extension and 80 for the mantissa. 
Maybe a huge overkill but it is simpler to scale down then start with 
single precision = 32 bits and the have to scale up. My format also 
allows me to handle up to 19 characters in a number like 
1234567890.987654321.
I started with programming the conversions in Pascal and then 
translating the source into assembly. Sources are free of course.


Today I also had a very nice day. A year ago in Belgium a man died who 
was a computer collector. His son and daughter had nothing with 
computers and decided to donate the whole collection to the Homecomputer 
Museum in Helmond (NL). They collected a lot and still there was a lot 
left like Wang servers and various Digital equipment.
Here is a link before we raided the barn:  https://youtu.be/yoWB9ePcgUs
Unfortunately no Commodores except two printers (just popped up: maybe 
already collected). I had opted for an ETAP 4200 (01:30) but someone had 
opted earlier. OTOH, I have scored the Aster, the computer you see 
before you start up the video and at 08:51. It is a Dutch made Z80. I 
also scored a programmer (04:12), three PCs: 05:56, the one with the 
yellow memo (8088) and the two at the right 80286s. TI/99 at 06:29 and 
the grey box at 06:44. It is a Philips laptop D33 or rebranded Olivetti 
D33 (or the other way around ???). Bondwell 14 at 06:53 and a Philips 
Videowriter at 10:22. Never seen and it looks like a printer with a 
screen, keyboard and floppy drive. Nobody wanted it so I took it home. 
As last I scored a Kaypro 4. Not to be seen on the video so nobody opted 
for it. I'm afraid I'm a bit busy for some time :)

If you wonder why I opted for the ETAP (= word processor, nothing else)? 
I didn't know it and I wanted something weird. But the guy that 
collected it already had an older type so he was really motivated to get 
it. And that Videowriter is weird enough as well.


-- 

Kind regards / Met vriendelijke groet, Ruud Baltissen

www.Baltissen.org
Received on 2022-09-24 17:00:26

Archive generated by hypermail 2.3.0.