[Haskell-cafe] Matters of precision
Andrew Coppin
andrewcoppin at btinternet.com
Thu Aug 9 13:47:04 EDT 2007
Hi folks.
I'm trying to write a Mandelbrot generator, and I've having a few
problems with precision.
First of all, currently I'm just using Double to represent coordinates.
Can anybody tell me what the smallest value you can represent with one
is? (Not including denormals.)
(I've built a function that checks for cycles in the orbit - by looking
for previous points that are sufficiently "near" to the current one. But
I want to know how much precision a Double gives me so I can figure out
how near is "near".)
Next up, at some point I'm going to need more precision than a Double
can give me. (But, obviously, I still want the thing to go as fast as
humanly possible.) In particular, I do NOT want to go into "infinite"
precision. (E.g., exact arithmetic with arbitrary fractions.) I want to
be able to make the precision arbitrarily high, but still finite and
fixed. (The idea being that the further you zoom in, the more the
computer turns up the precision.) Is there anything useful for this in
the standard libraries? Or will I have to write something?
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