The reason I'm looking for a way to run a true 64 bit double on the processor is to be able to run a version of this:
http://www.psa.es/sdg/sunpos.htm
for use in a stand alone heliostat.
I understand that the current IDE support for the arduino does not support a 64 bit double, which is why I wrote this post. If it did, I wouldn't be here.
I've been looking at some of the AVR compilers, specifically this one:
http://www.mcselec.com/index.php?option=com_content&task=view&id=14&Itemid=41
which claims to support a full 8 byte double on the ATmega. I'm wondering if anyone has ever tried using this, and how it worked for them.