[J3] branch based on ieee class ?

[Dan Nagle]

Hi,

Yes, I didn't read far enough.

But neither of the compilers I'm targeting support == and /=  :-(


> On Nov 7, 2019, at 09:42 , Vipul Parekh via J3 <j3 at mailman.j3-fortran.org> wrote:
> 
> Hello Dan,
> 
> See section 17.2 Derived types, constants, and operators defined in
> the modules in 18-007r1.pdf, p3 on IEEE_ARITHMETIC module,
> particularly lines 27 thru' 30 which state,
> 
> 27 * The pure elemental operator == for two values of one of these
> types to return true if the values are the
> 28   same and false otherwise.
> 29 * The pure elemental operator /= for two values of one of these
> types to return true if the values differ and
> 30   false otherwise.
> 
> From what I understand, you will have to construct your case using
> either of the above-mentioned operators e.g.,
> 
>   use, intrinsic :: ieee_arithmetic, only : ieee_class,
> ieee_negative_normal, operator(==)
>   real :: x
>   x = -1.0
>   if ( ieee_class(x) == ieee_negative_normal ) then
>      print *, "x is IEEE_NEGATIVE_NORMAL"
>   else
>      print *, "The IEEE class of x is not as expected!"
>   end if
> end
> 
> Upon execution, the program output is expected as:
> x is IEEE_NEGATIVE_NORMAL
> 
> Regards,
> Vipul Parekh
> 
> On Thu, Nov 7, 2019 at 10:38 AM Dan Nagle via J3
> <j3 at mailman.j3-fortran.org> wrote:
>> 
>> Hi,
>> 
>> How to?
>> 
>> C1145 removes the select case option (my first choice), and
>> Table 10.2 eliminates if-blocks by not listing ieee_class_type
>> among the allowed operands for == and /= (or .eqv. and .neqv.).
>> 
>> I'm writing a workshop on ieee 754 and I would like to write
>> a diagnostic routine that can print "this is an X" where
>> X is one of the ieee_class_type values.  So I want to branch
>> to select the correct label per class.
>> 
>> (With the select case, a range of values does not seem to make sense.
>> But I want to case each one singly, so that's no matter to the task at hand.)
>> 
>> 
>> --
>> 
>> Cheers!
>> Dan Nagle
>> 
>> 


--

Cheers!
Dan Nagle