Mail Archives: djgpp/2001/07/06/19:30:10
On Wed, 04 Jul 2001 19:49:21 GMT, invalid AT erehwon DOT invalid (Graaagh the
Mighty) wrote:
>On Wed, 04 Jul 2001 20:30:20 +0300, "Eli Zaretskii"
><eliz AT is DOT elta DOT co DOT il> sat on a tribble, which squeaked:
>
>>In any decent course in numerical computation, the first lesson
>>teaches you that you cannot even solve a quadratic equation without
>>risking numerical pitfalls.
>
>Newton's method? That does division, iteratively. The quadratic
>formula? I doubt you'll have trouble with numerical instability except
>right on the threshold of zero.
try google - you're quest is to find the paper "What every Computer
Scientist should know about floating point arithmetic." It meets at
least one of your oft stated requirements - it's free. Unfortunately
it's technical and requires actual reading. It's a very good
description of the trials and tribulations of floating point.
>Now please stop spouting your "numerical wisdom" and give some real,
>usable information about what might cause what was observed, given
>that all I did was assign some numbers to some doubles/long doubles
>and perform a few arithmetic operations on them -- not even inside of
>a loop.
I can't speak for Eli, but you sure have a strange way of asking for
help. I don't know how Eli will respond but I'm not interested in
doing your homework. The "numerical wisdom" is the result of some very
serious study by people who aren't afraid of "bucky bits".
As for your code problems, you should consider the possibility very
real that noone here is going to be of much help to you without seeing
your code or some better examples.
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