Safe addition: Difference between revisions

</pre>

=={{header|Hare}}==

{{trans|C}}

<lang hare>use fmt;

use math;

type interval = struct {a: f64, b: f64};

export fn main() void = {

const a: [_](f64, f64) = [

(1.0f64, 2.0f64),

(0.1f64, 0.2f64),

(1e100f64, 1e-100f64),

(1e308f64, 1e308f64)];

for (let i = 0z; i < len(a); i += 1) {

let res = safe_add(a[i].0, a[i].1);

fmt::printfln("{} + {} is within ({}, {})", a[i].0, a[i].1, res.a, res.b)!;

};

};

fn safe_add(a: f64, b: f64) interval = {

let orig = math::getround();

math::setround(math::fround::DOWNWARD);

let r0 = a + b;

math::setround(math::fround::UPWARD);

let r1 = a + b;

math::setround(orig);

return interval{a = r0, b = r1};

};</lang>

{{out}}

<pre>

1 + 2 is within (3, 3)

0.1 + 0.2 is within (0.3, 0.30000000000000004)

1e100 + 1e-100 is within (1e100, 1.0000000000000002e100)

1e308 + 1e308 is within (1.7976931348623157e308, Infinity)