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From: "J-P. Rosen" <rosen@adalog.fr>
Newsgroups: comp.lang.ada
Subject: Re: small example, using complex variables in Ada
Date: Thu, 10 Jun 2010 11:12:10 +0200
Organization: Adalog
Message-ID: <huqa9h$276$1@news.eternal-september.org>
References: <hunrki$ph7$1@speranza.aioe.org> <82ljannyeq.fsf@stephe-leake.org>
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Date: 2010-06-10T11:12:10+02:00
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Stephen Leake a �crit :
>> -- 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.
In Ada, the value is rounded to the requested accuracy (A.10.9(25)). In
Fortran, the machine value is printed.

> It would be good to state the theoretically correct answer; I hope it's
> 1.5, not 1.499... :).
Note that they are mathematically equal (with an inifinite number of 9s)
-- 
---------------------------------------------------------
           J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr