double trouble

[John C]

"Don Clugston" <dac at nospam.com.au> wrote in message 
news:du48kq$i5i$1 at digitaldaemon.com...
>
> The trick to maximal efficiency in these conversions is to make sure that 
> you only do ONE division (because that's the point at which the rounding 
> error occurs). Don't divide by 10 every time, and definitely don't use 
> pow. Instead, keep track of a denominator, and every time you'd do a 
> v/=10, do denominator*=10 instead. Then, right at the end, divide v by 
> denominator.
> The reason this works is that integers can be exactly represented in 
> reals, so the multiplies aren't introducing any error. But every time you 
> divide by something that isn't a multiple of 2, a tiny roundoff error 
> creeps in.
> You'll also reduce the error if you use
> real v=0.0;
> instead of double. Even if you ultimately want a double.

Thanks. Working on the raw bits (actually a 64-bit integer) eventually 
proved easier (relatively speaking).