(j3.2006) REAL with NaN argument

[Bill Long]

On Jul 2, 2014, at 6:30 PM, Van Snyder <Van.Snyder at jpl.nasa.gov> wrote:

> Should one expect
> 
>  double precision :: D
>  D = IEEE_Value(1.0e0,IEEE_Signaling_NaN)
> 
> to produce a double-precision signaling NaN?

Don?t think so.  If you want a double precision signaling NaN, try this:

D = IEEE_Value( 1.0d0, IEEE_Signaling_NaN)

or, safer (in my opinion)

D = IEEE_Value( D, IEEE_Signaling_NaN)

We have weasel words that allow the processor to cop out on this (14.11.37p8), but the above has worked on all the systems I?ve used since IEEE hardware was included.

Cheers,
Bill

> 
> 7.2.1.2, 7.2.1.3 (in particular, tables 7.8 and 7.9), and 13.7.138,
> don't mention IEEE exceptional values.  Should they?
> 
> 
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Bill Long                                                                       longb at cray.com
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