Accuracy problem in spreadsheet in Geogebra 5
It seems that there is a problem in Geogebra 5 spreadsheet in comparisons when the number
is small. The version I have is 5.0.631.0-d
=If(-0.00000000121248 < 0, -1, 1) gives 1 instead of the correct -1
The same problem appears in the Algebra-window. However, in the CAS it gives the correct
If(-0.00000000121248<0, -1, 1) -> -1
Constructs like this are used for instance in numerical root-solving called
the bisector algorithm. Due to this problem, it is not possible to trust the result
given by Geogebra.
The same problem seems to be in Geogebra 6, at least in the version I have, namely
6.0.631.0. However, I don't really use the version 6, because I like more the user interface
of Geogebra 5.
I tried changing the rounding to 15 significant figures, but that didn't seem to help.