From: sgk@REMOVEtroutmask.apl.washington.edu   
      
   On Sat, 16 Aug 2025 20:40:13 -0500, Gary Scott wrote:   
      
   > On 8/16/2025 7:02 PM, Steven G. Kargl wrote:   
   >> On Fri, 15 Aug 2025 22:24:52 +0000, Lawrence D’Oliveiro wrote:   
   >>   
   >>> On Thu, 14 Aug 2025 11:21:00 +0800, Woozy Song wrote:   
   >>>   
   >>>> A program was going wrong, and found   
   >>>> FRACTION(3.75)=0.9375 and FRACTION(2.5)=0.9375   
   >>>   
   >>> Broken as designed, according to the spec.   
   >>>   
   >>> Why on Earth does FRACTION have this meaning?   
   >>   
   >> To what spec are you referring?   
   >>   
   >> gfortran is giving the correct answer (although   
   >> I suspect OP has a transcription problem with   
   >> the second example).   
   >>   
   >   
   > I think most casual, non-math, non-floating point experts would expect this:   
      
   For someone programming in the Fortran language, I would expect   
   that they would consult some form of documentation to learn why   
   their expectation might be wrong.  For example, the gfortran   
   documentation (which comes with the compiler) contains   
      
      
   8.119 ‘FRACTION’ -- Fractional part of the model representation   
   ===============================================================   
      
   _Synopsis_:   
        ‘Y = FRACTION(X)’   
      
   _Description_:   
        ‘FRACTION(X)’ returns the fractional part of the model   
        representation of ‘X’.   
      
   _Class_:   
        Elemental function   
      
   _Arguments_:   
        X           The type of the argument shall be a ‘REAL’.   
      
   _Return value_:   
        The return value is of the same type and kind as the argument.  The   
        fractional part of the model representation of ‘X’ is returned; it   
        is ‘X * RADIX(X)**(-EXPONENT(X))’.   
      
   _Example_:   
             program test_fraction   
               real :: x   
               x = 178.1387e-4   
               print *, fraction(x), x * radix(x)**(-exponent(x))   
             end program test_fraction   
      
   --   
   steve   
      
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