Rockbox mail archiveSubject: Re: Math in Rockbox
Re: Math in Rockbox
From: Andreas Stemmer <groovingandi_at_gmx.de>
Date: Thu, 7 Jul 2005 08:35:09 +0200 (MEST)
> For an upcoming patch, I need some fixed- or floating-point math. Does
> a good fixed-point implementation of pow(10, x) (or exp10(x)), or some
> on how to implement it? It doesn't need to be particularly fast; small
> is to be preferred actually.
If x is an integer value, use one of the algorithms already given (lookup
table or while loop). If x can be fixed point as well, you could use some
kind of taylor approximation:
e^x = x^0/0! + x^1/1! + x^2/2! + x^3/3! + ...
with 10^x = (e^n)^x = e^(n*x)
and n = ln 10 = 2.302585093
for an implementation see
Received on 2005-07-07