linuxaudio.org

On Fri, Jan 28, 2011 at 02:02:36PM +0100, Philipp Überbacher wrote:
> rant_begin

quoted text
>     Why can't log mean the same thing everywhere? Why does it need to be

>     base e here and base 10 there? Why is there no consistency?

>     And why is there no proper logarithmus dualis function? Because you

>     can simply do log(n)/log(2)? We've just seen how well this works.

>     How about:

>         log() - base 10

>         ln() - base e - logarithmus naturalis

>         ld() - base 2 - logarithmus dualis

> rant_end

Libm has log(), log10, and log2().
> The next obvious question is: Does the inaccuracy reliably result in

quoted text
> values bigger than 11?

No.
If the input is a power of two, and you expect an integer as

a result, just do
  k = (int)(log2(x) + 1e-6)
or
  k = (int)(log(x)/log(2) + 1e-6)
or
  int m, k;

  for (k = 0, m = 1; m < x; k++, m <<= 1);
  which will round up if x is not a power of 2.
Ciao,
--

FA
There are three of them, and Alleline.
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