Re: power() (to Rob)
Rolf Schroeder writes:
> But now I'm convinced that the
> function power(), which probably relies on the C function pow(), is not
> correctly implemented into Euphoria. I compared pow() (Quick C) and
> power() (Euphoria) by the following examples:
> ...
> Could it be that the WATCOM C behaves different in comparison
> to (good old) Quick C ?
Your examples work fine with Euphoria on Windows, Linux and FreeBSD.
They also work fine with WATCOM C on DOS, provided the /fpc
(floating-point calls) option is not used. Euphoria for DOS is built using
WATCOM's /fpc option. It allows Euphoria programs to run on old 486's and 386's
that lack floating-point hardware. When /fpc is used, floating-point C routines
are called, rather than generating in-line floating-point hardware instructions.
The routines in most cases check if f.p. hardware is present and use it,
but the results of these routines can vary slightly from the in-line approach.
The floating-point registers on Intel CPU's are actually 80 bits wide,
not 64 bits. That means there is extra precision in performing
a series of calculations, as long as the numbers are kept in the f.p.
registers. When a result is stored in memory as a C double (Euphoria atom)
it is rounded to 64 bits. So it should be more accurate
to do in-line f.p., rather than a series of calls, that can only pass 64 bit
intermediate results as arguments to these f.p. routines.
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
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