Re: [Gnuplot-info] integer vs. floating point division

[Tait <gnu...@t4...>]

> > > > ceil(900e-7/12e-7) => 76.
> > > ...
> > That particular example will "misbehave" even with 64b doubles
> > (or at least it did in my test, which is why I used that
> > particular example).
> 
> It does not misbehave here  in gnuplot (linux x86-64 platform)
> 
> I tried a few larger exponents at random, up to
> ceil(900e-101/12e-101), without tripping an error.
> Is there some particular pattern that is prone to error?

Sorry; I meant it misbehaves in a dumb little C++
program I was using to test, not in gnuplot.

#include <iostream>
#include <ios>
#include <iomanip>
#include <cmath>

int main() {
    double num1 = 900e-7;
    double num2 = 12e-7;
    std::cout << std::setprecision(30) << std::fixed
        << num1 << std::endl
        << num2 << std::endl
        << num1/num2 << std::endl
        << std::ceil(num1/num2) << std::endl;
    return 0;
}

Although as you say, it doesn't go to 76 in gnuplot,
which makes me wonder why it behaves differently.