[fitsbits] 16-bit floats {External} {External}

[James E.H. Turner]

+1 for what it's worth... It sounds like any existing, higher-level
software that expects to work with ordinary image or table extensions
but now wants to support short floats would have to accommodate a whole
new extension type, rather than simply some new header codes?? While
radio astronomy might be the driving use case, there are bound to be
others, where people simply want to vary the precision without the
whole structure changing.

Cheers,

James.


On 25/07/2025 20:27, Paul Hirst via fitsbits wrote:
> Hi all,
> 
> My 2c worth on all this.
> 
> I would support updating the standard to include both 16 and 128 bit floats as 
> both image and binary table data types. My instinct is to just update the 
> standard rather than going with an extension.
> 
> I don't think it follows that this forces all packages to update - as far as I'm 
> aware there's nothing that says every package has to support all possible FITS 
> files. Obviously, if you want to make use of the new types, you'd need to use 
> software that supports them, but that's only the same as for example if you want 
> to use tables, or tile compression, you need to use software that supports them.
> 
> Paul.
> 
> 
> On Fri, Jul 25, 2025 at 1:56 PM Preben Grosboel via fitsbits 
> <fitsbits at listmgr.nrao.edu <mailto:fitsbits at listmgr.nrao.edu>> wrote:
> 
>     Hi Fitsbits,
>     Although retired I still have a private opinion.
>     Allowing a new data type in the primary header would in principle force all
>     readers to be upgraded. A significant request.
>     A better way would be to create a new extension type for radio astronomy.
>     This would give full freedom to include any format or feature needed without
>     forcing old readers to be upgraded.
>     Yours
>     Preben Grosboel
> 
>     --
>     Sent with GMX Mail app
> 
> 
>     On 7/25/25, 17:44 Maren Purves via fitsbits <fitsbits at listmgr.nrao.edu
>     <http://listmgr.nrao.edu>> wrote:
> 
>         As another one who also dates back to the days of punched cards, the
>         80 character length is what the punched cards had, 80 characters, 7
>         bit ASCII.
> 
>         I'm glad Malcolm got back to doing some astronomical research after
>         retiring.
> 
>         Maren (nominally head of instrument and telescope software at the East
>         Asian Observatory/JCMT but really more of a sysadmin these days)
> 
>         On Thu, Jul 24, 2025 at 11:24 PM Malcolm J. Currie via fitsbits
>         <fitsbits at listmgr.nrao.edu <http://listmgr.nrao.edu>> wrote:
>          >
>          > > Just because we are old does not mean that we are not working on
>         state-of-the art software. The reason for wanting 16-bit floats is for this
>          > > specific reason. Radio astronomy software would benefit from 16-bit
>         floats.
>          >
>          > Absolutely. That realisation had crossed my mind at the time, and I
>          > wondered whether to qualify my statement. The groups weren't mutually
>          > exclusive. In the end I decided not to dilute the point that we do need
>          > fresh blood in the FITS WG.
>          >
>          > Malcolm
>          >
>          >
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