Vivaldo writes:
> Dear Sir,
>
> I have found a difficult do work with long double. I have written a
> simple test code and compiled it with gcc 4.0.0. The code was the following
>
> #include <cmath>
> #include <iostream>
>
> using namespace std;
>
> main(){
>
> long double x,y,a;
> x = 1.000000000000001; //(1 at 15th decimal place)
> y = 1.000000000000002; //(idem)
> a = y - x;
> cout.precision(30);
> cout << a << endl;
> }
>
> Surprinsingly, the output written in the screen was not
>
> 1.0000....e-15
>
> with 19 correct decimal places. Instead the result was
>
> 8.88178419700125232338905334473e-16
>
> with error at the 16-th place!
>
> How should I proceed to have the precision of 19 significative digits?
This list is not for general gcc enquiries, but for the development of
gcc itself. Please address queries to gcc-help.
This is not a bug. The type of a floating-point literal is double by
default, not long double. See Section 2.13.3 of the C++ Standard,
"floating literals"
Andrew.
