🚀 go-pugleaf

In article <20285@bcsaic.UUCP> carroll@bcsaic.UUCP (Jeff Carroll) writes:
>In article <KHB.90Feb12174730@chiba.Eng.Sun.COM> khb@chiba.Eng.Sun.COM (Keith Bierman - SPD Advanced Languages) writes:
>>
>>IEEE double is large enough that quad precision (*32) isn't needed. I
>>neglected to be specific in my previous posting. _roughly_ speaking
>>ieee dp is good from 10**-308 to 10**+308. 
>>
>
>	This reminds me of the answers I used to get from a certain
>vendor of test equipment based in Palo Alto. When I thought of a
>really creative application for one of their boxes, the salesman would
>ask, "Why would you want to do THAT???"
>
>	The WHOLE POINT is that some of us think that we *may need*
>COMPLEX*32.
>

I don't know about COMPLEX*32, but REAL*16 is most surely needed - 
I used to do classical mechanics of molecules. THE differential
equations are unstable - they generate chaotic solutions.
Errors for any reason, including roundoff, grow exponentially
with time (and number of integration steps, as these equations
need fixed step size integrators). Thus to double the length of time
you get "correct" answers, you must doubel the word length.
To get useful results you may NEED REAL*16, and to verify that
a computation for which REAL*8 is good enough by back-integration,
you need REAL*16.

Doug McDonald