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Excerpts from Peter Nelson's message of 2011-01-28 13:03:56 +0100:

quoted text
> On Fri, 2011-01-28 at 12:28 +0100, Philipp Überbacher wrote:

>

> > Interesting.. would you mind explaining how this can be?

> > How can 11-11 yield 4.80518e-16?

>

> Because, rather than 11, log(2048)/log(2.0) is actually (to 40 d.p.)

>

> 7.6246189861593984035895533360399422488305 /

> 0.6931471805599453094172321214581765680755

>

> But doubles don't contain 40 d.p.; it is approximately 16. Thus some

> rounding errors may occur...

>

> Peter.

Thanks Peter, this section was supposed to refer to the output of the

test program. cout printed 11 for both values but 4.80518e-16 for one

value minus the other, so this at least a very nasty inconsistency.
I still don't understand why this results in 11 on some machines and

something else on others. 32/64 bit? Compiler differences? Luck?
rant_begin

    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
The next obvious question is: Does the inaccuracy reliably result in

values bigger than 11?
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