Re: Is real(16) available on x86 platforms?

[Erik Schnetter <schnetter at cct dot lsu dot edu>]

On Jan 14, 2007, at 09:46:57, Steve Kargl wrote:

> On Sun, Jan 14, 2007 at 03:52:48PM +0100, Dominique Dhumieres wrote:
> > Trying to use real kind 16 on x86_64-unknown-linux-gnu
> > gfortran from gcc version 4.3.0 20061231, I get:
> >
> > Error: Invalid real kind 16
> >
> > Is real(16) available only on platforms not supporting
> > real(10)?
>
> Your question is sort of wrong.  real(16) is available on
> targets that support a 128-bit floating point type.  If
> this FP is unavailable on the target, then real(16) is also
> unavailable.  On these targets one sometimes fines an
> 80-bit FP type, so gfortran provides a real(10) (which I
> believe is padded out to 16 bytes).

I think real(10) is "usually" padded to 12 bytes (on IA32 machines).   
When the option -m128bit-long-double is given, it is padded to 16  
bytes.  That means the kind number encodes the accuracy, not the  
number of bytes.

-erik

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Erik Schnetter <schnetter@cct.lsu.edu>

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