Re: small example, using complex variables in Ada

[Simon Wright <simon@pushface.org>]

"Nasser M. Abbasi" <nma@12000.org> writes:

> On 6/10/2010 12:23 AM, Stephen Leake wrote:
>
>>
>>> -- gnatmake dft.adb
>>> --
>>> -- ./dft.exe
>>> -- ( 6.00000E+00, 0.00000E+00)
>>> -- (-1.50000E+00, 8.66026E-01)
>>> -- (-1.50000E+00,-8.66025E-01)
>>> -- $
>>>
>>> ======= FORTRAN code ===========
>>> ! dtf.f90, compiled with GCC 4.3.4
>>> ! under CYGWIN 1.7.5
>>> ! gfortran -Wall dft.f90
>>> ! ./a.exe
>>> ! (  6.0000000    ,  0.0000000    )
>>> ! ( -1.4999999    , 0.86602557    )
>>> ! ( -1.5000005    ,-0.86602497    )
>>> !
>>
>
>> It would be good to explain the small differences here; something about
>> how the floating point options are set, I suspect.
>>
>
> Yes, I noticed that too. Need to look more into. It could be just a
> formating thing. I just used Print*, in Fortran becuase at the time
> was too lazy to lookin up the other formating functions in Fortran. In
> Ada, I used the predefined Put on Complex of float types.

I tried with
   put(X(k), Aft => 8, Exp => 0); new_line;
(to match the number of digits output by the Fortran) and got

( 6.00000000, 0.00000000)
(-1.49999988, 0.86602557)
(-1.50000024,-0.86602497)

so I think it's just a formatting thing (though that -1.50000024 looks a
little off; but Float is digits 6 on this hardware - Macbook Pro, so
those last 3 digits are spurious).