[AstroPy] unexpected pyfits behavior float32 converted to float64

[Michael Droettboom]

It actually appears that this is converting 32-bit integers to 64-bit 
floats.  Does the file have BZERO or BSCALE specified?  If so, it is 
normal behavior to convert to 64-bit floats so that user code doesn't 
have to deal with offset and scaling issues.

Mike

On 05/08/2012 02:14 PM, Jim Vickroy wrote:
> On 5/8/2012 11:11 AM, Philip Tait wrote:
>> Isn't this a known issue, fixed in 3.0.7?
>
> Thanks for the quick reply.  It is embarrassing to post a problem and 
> not be using the latest release.  So I've downloaded/installed 3.0.7.  
> Unfortunately, the same behavior persists (i.e., unwanted, silent 
> conversion from 32 to 64 bit floats) as illustrated below:
>
> >>> import os
> >>> import sys
> >>> import pyfits
> >>> sys.version
> '2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)]'
> >>> pyfits.__version__
> '3.0.7'
> >>> path = ...
> >>> HDUs = pyfits.open (path,mode='readonly')
> >>> HDUs['primary'].header['bitpix']
> 32
> >>> HDUs['primary'].data.dtype
> dtype('float64')
> >>> HDUs['primary'].header['bitpix']
> -64
> >>>
>
> Is this a bug that should be reported?
>
> Thanks,
> -- jv
>
>
>
>
>
>
>>
>>
>>
>> -- Sent from my HP Pre3
>>
>> ------------------------------------------------------------------------
>> On May 8, 2012 6:59, Jim Vickroy <jim.vickroy at noaa.gov> wrote:
>>
>> Hi Pyfits users,
>>
>> Consider:
>>
>> >>> import pyfits
>> >>> pyfits.__version__
>> '3.0.5'
>> >>> path = ...
>> >>> HDUs = pyfits.open (path,mode='readonly')
>> >>> HDUs['primary'].header['bitpix']
>> 32
>> >>> HDUs['primary'].data.dtype
>> dtype('float64')
>> >>> HDUs['primary'].header['bitpix']
>> -64
>> >>>
>>
>> Why is the conversion from 32 to 64 bit floats silently occurring? How
>> can I prevent it?
>>
>> Thanks,
>> -- jv
>>
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>
>
>
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