Comment 48 for bug 1411958

OK, thanks.
NaN is no longer produced because I avoid the (totally unexpected before) division by zero.

In RefractionExtinction.cpp near line 120 and 176 I currently replace occurences of zero eyepoint by 0/0/1, which apparently creates the different appearance of the flicker-state moon. but it still means there is zero-eyepoint under some circumstances.

Nick, can you try to replace in the line following, "altAz[2]=1;" by simple "return;".

If this fails to stop it, we need to get deeper into the matrix stuff.