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<title>RE: [vtk-developers] isnan</title>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><!-- Converted from text/plain format -->David,</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>You’re probably right about MSVC 6
but for those of us who are stuck with it, the following may be useful.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>John.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>static int IsNaN(const double x)</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>{</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> unsigned int e_mask, f_mask;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> double as_double = x;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> unsigned int *as_int;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> vtkByteSwap::Swap8BE(&as_double);</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> as_int = (unsigned int *)&as_double;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> vtkByteSwap::Swap4BE(as_int);</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> e_mask = 0x7ff0;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> e_mask <<= 16;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> if ((*as_int & e_mask) != e_mask)</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> {</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> return 0;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> }</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> f_mask = 1;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> f_mask <<= 20;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> f_mask--;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> return (*as_int & f_mask) != 0;</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>}</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal style='margin-left:36.0pt'><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'>-----Original Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> vtk-developers-bounces+jcplatt=dsl.pipex.com@vtk.org
[mailto:vtk-developers-bounces+jcplatt=dsl.pipex.com@vtk.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Thompson, David C<br>
<b><span style='font-weight:bold'>Sent:</span></b> </span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>14 January 2007</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> </span></font><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>00:10</span></font><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'><br>
<b><span style='font-weight:bold'>To:</span></b> Michael Halle;
vtk-developers@vtk.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: [vtk-developers]
isnan</span></font></p>
<p class=MsoNormal style='margin-left:36.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'> </span></font></p>
<p style='margin-left:36.0pt'><font size=2 face="Times New Roman"><span
style='font-size:10.0pt'>> In the mean time, how about the question of where
to put<br>
> the actual isnan function in VTK, hopefully in a way that<br>
> introduces as little overhead as possible? Is vtkstd::isnan()<br>
> the right place (since that's analogous to std::isnan() )?<br>
<br>
Note that vtkMath already has static member functions<br>
Inf(), NegInf(), and </span></font><font size=2><span style='font-size:10.0pt'>Nan</span></font><font
size=2><span style='font-size:10.0pt'>() that return constants. If isnan<br>
is placed in vtkstd, then these functions should also move<br>
there. I would prefer vtkMath::IsNan() though. Also, I'm under<br>
the impression that some of the compilers that Kitware wishes<br>
to support (*cough*MSVC 6*cough*) don't have isnan() at all -- but<br>
I could easily be wrong about that as I am not a Windows person.<br>
<br>
David</span></font> </p>
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