Re: [Gnuplot-info] int() strange behaviour

[Hans-Bernhard B. <HBB...@t-...>]

On 07.07.2012 01:45, Simon Garfunkel wrote:

> Anyway in my particular situation these "missed approximations"
> have a disastrous effect, since I'm creating classes for an hystogram:
>
> gnuplot> print int(19.1/0.1)
> 191
> gnuplot> print int(19.2/0.1)
> 191
[...]
> Undoubtedly unconvincing classes.

That's because you put your class boundaries exactly on those points 
where you want to check.  In effect you're comparing floating-point 
numbers for exact equality, which is never a good idea.  Hence that 
"hardly ever 1.0" line I quoted earlier.

Yes, you could use an offset.  But ultimately nothing can really help. 
Wherever you place your class boundaries, sometimes the inevitable 
floating-point round-off _will_ move data right across that boundary.