[fitsbits] INF/NAN as header values?

[Mark Calabretta]

On Fri 2013/06/07 15:14:28 -0400, William Pence wrote

>There are, however, several simple alternatives one could use that would 
>be conforming.  In the case of NaNs, one could,

 ...

>2) write it as a string, as in "DATAMIN = 'NAN'      ", or

 ...

>In the case of INF values (which are less commonly used than NaNs), the 
>only alternative that comes to mind is to enclose it in quotes as in
>
>DATAMAX = 'INF'

Section 4.4.2.5 of the FITS standard says:

  DATAMAX Keyword  The value field shall always contain a floating-point
  number, regardless of the value of BITPIX.  ...

Existing FITS header parsers have been programmed to look for a floating
point number, not a string nor a blank field.  Likewise for DATAMIN.

Regards,
Mark Calabretta