The ‘zero‘ value is the default threshold for values approaching 0.0.
Syntax:
set zero <expression>
show zero
‘gnuplot‘ will not plot a point if its imaginary part is greater in magnitude than the ‘zero‘ threshold. This threshold is also used in various other parts of ‘gnuplot‘ as a (crude) numerical-error threshold. The default ‘zero‘ value is 1e-8. ‘zero‘ values larger than 1e-3 (the reciprocal of the number of pixels in a typical bitmap display) should probably be avoided, but it is not unreasonable to set ‘zero‘ to 0.0.