On 01/15/18 15:38, Yuri Pankov wrote:
Hi,
Looking at https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=217149, I
noticed that it isn't a seq(1) problem per se, rather for() and while()
loops behaving inconsistently while using floating point, i.e.:
double i;
for (i = 1; i <= 2.00; i += 0.1)
printf("%g\n", i);
would produce:
1
...
1.9
but:
double i;
for (i = 1; i <= 2; i += 0.2)
printf("%g\n", i);
would correctly end with 2:
1
...
2
Hi,
The decimal value "0.2" is the same like the fraction "1/5", which
cannot be represented by a float nor double without rounding error. The
more times you iterate the bigger the error becomes.
When you compare an integer with a float rounding happens. Check this out:
if ((int)(float)0.999999999999999999999 >= (int)1)
printf("OK\n");
Sequences using floating point should technically only use steps which
can be written like this: "remainder * pow(2, -shift)".
--HPS
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