Is there a simple way to distinguish -0 from 0 in l3fp?

I had been aligning left in a table a column of sines, +0 or -0 followed 
by decimal point & digits. By adding an \hphantom{-} before the positive 
numbers, they aligned nicely on the decimal point in the column, but 
then along came -0. The simple conditional, "if !(number < 0) add 
phantom", added the phantom and the column aligned like
  0
  0.5878
  -0
-0.5878
etc.
In the absence of formatted printing of numbers, -0 is a problem. Even a 
built-in test for -0 would ease matters, since in any kind of formatted 
printing of numbers 0 and -0 will generally require different handling.

As it is, I've had to test each fp for whether it is zero; if it is I 
convert to a tl variable and test whether that is -0. This is clumsy. 
Hence my opening question.

Andrew

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