Re: How to check a Float for NaN

[anon@anon.org (anon)]

If you look at my first post on this topic and change the 16#FF000000# 
to 16#7F000000# (typo, forgot to adjust for the sign-bit) its basically 
what I have done except that I use a 64-bit sign integer instead of the 
Unsigned_64.  In order to save coding time, did not want to add the
extra statements. Plus, if it for a final (it that time of the year) they 
should be able add those lines.

And because float is normally defined by the IEEE-754 as a 32-bit 
number it will fix into a 64-bit integer without raising a 
Constraint_Error.  The size of Long_Long_Integer is at least 64-bit 
signed integer on a 32/64 bit machines.

NaN := range 2#0111_1111_1111_0000_0000_0000_0000_0000# 
               ..
               2#1111_1111_1111_1111_1111_1111_1111_1111#  ;


In <12227360.svS57WvVVs@linux1.krischik.com>, Martin Krischik <krischik@users.sourceforge.net> writes:
>Jerry wrote:
>
>> How would one check a Float or Long_Float if it has value NaN? The
>> only ways that I can come up with are to import a C function (isnan, I
>> think) or to write Long_Float'image(Some_Float) to a string and
>> examine the first three characters to see if they are "NaN" (and that
>> seems to be a GNAT implementation choice so might not be portable,
>> which is OK for my use).
>
>How about an Unchecked Conversion to an Unsigned_64 and comparing
>>2#0111_1111_1111_0000_0000_0000_0000_0000#
>
>Note that it's '>' as 2#0111_1111_1111_0000_0000_0000_0000_0000# is positive
>infinity.
>
>Martin
>-- 
>mailto://krischik@users.sourceforge.net
>Ada programming at: http://ada.krischik.com