fma

Fused multiply-add: $x * $y + $z with a single rounding.

Synopsis

my $r = POSIX::fma($x, $y, $z);

What you get back

A double. Because there is only one rounding step, the result can be more accurate than the naive two-step expression, especially for catastrophic-cancellation patterns like $a * $b - $c * $d rewritten as fma($a, $b, -($c * $d)).

Differences from upstream

Fully compatible with upstream POSIX.