Re: [Sdcc-user] single precision - computing sidereal time

[JuanPi <ju...@dw...>]

Hi,

If you realy are into numerics, you can emulate doubles using floats.
Here are some pointers
http://stackoverflow.com/questions/6769881/emulate-double-using-2-floats
At the endo of the day everythign is an integer, so you can always re
implement double precision (from your link you will need operators -,
+, * and function sin).

The issue there is you are going to be doing a lot of bookkeeping (you
will be reinventing the wheel :D).
If you go this way I suggest you first test all you programs in a easy
to use language (Octave, Python, etc) using floats and integers.

Of course it would be easy just to find a compiler with double support.

Good luck.


On Wed, Jul 9, 2014 at 12:42 PM, Daniel Michalik <sd...@bl...> wrote:
> Dear all,
> I'm trying to implement a conversion from solar (regular) time to
> sidereal time for astronomical purposes on a PIC16F1938. As far as I
> understand sdcc supports single precision only. I would like to ask for
> advice how to proceed. For the calculations necessary for the time
> conversion see http://aa.usno.navy.mil/faq/docs/GAST.php.
> I do not see how I could do this in single precision, but I'd love to
> hear some advice of people more experienced with microprocessor
> programming and sdcc.
>
> - Do I need to change to a different compiler than sdcc?
> - Can double precision floating point operations be emulated in a
>   straight forward way within sdcc?
> - Is there a way to reformulate the conversion to be correct with single
>   precision calculations?
>
> Kind regards,
> Daniel
>
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