One again, from srfi-48:
===============
If the number it too large to fit in the width specified, a string longer than
the width is returned

(format "~1,2F" 4321) => "4321.00"

...

For very large or very small numbers, the point where exponential notation is
used is implementation defined.

(format "~8F" 32e5) => "   3.2e6" or "3200000.0"
===============

Note that the number of digits after the decimal point is as specified.

Cheers,
-KenD

===============
On Friday 11 June 2004 04:49 am, soo wrote:
> The following seems to be a bug of FORMAT.
>
> > (format "~8,3F" 3.4569e15)
>
> "3.456e+15"
>
> > (format "~8,3F" 3.4569)
>
> "   3.457"
>
> > (format "~8,2F" 3.456e15)
>
> "3.45e+15"
>
> > (format "~8,2F" 3.456)
>
> "    3.46"