[Numpy-discussion] long double woes on win32

Travis E. Oliphant oliphant@enthought....
Sat Aug 16 10:50:53 CDT 2008


Charles R Harris wrote:
>
>
> Yes. I don't think MS will support "true" long doubles any time soon 
> and this affects printing and the math functions. I'm not sure what 
> the best solution is, there are various possibilities.
>
> 1) We could define the numpy longdouble type to be double, which makes 
> us compatible with MS and is effectively what numpy compiled with MSVC 
> does since MSVC long doubles are doubles. Perhaps this could be done 
> by adding a -DNOLONGDOUBLE flag to the compiler flags and then 
> defining longdouble to double. But this means auditing the code to 
> make sure the long double type is never explicitly used so that the 
> mingw compiler does the right thing. I don't think this should be a 
> problem otherwise except for the loss of "true" long doubles and their 
> extra bit of precision.
All code in numpy uses npy_longdouble which is typedef'd to double if 
SIZEOF_LONGDOUBLE is the same as SIZEOF_DOUBLE.   I don't understand why 
it's a problem to just define SIZEOF_LONGDOUBLE = 8 for mingw which is 
what it is for MSVC.    This makes longdouble 8 bytes.   

-Travis



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